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diff --git a/docs/contributing/development_tools.md b/docs/contributing/development_tools.md index a11e7beff..505928467 100644 --- a/docs/contributing/development_tools.md +++ b/docs/contributing/development_tools.md @@ -32,1068 +32,6 @@ Format the code: deno run -A --unstable ./tools/format.js ``` -### Profiling - -To start profiling: - -```sh -# Make sure we're only building release. -# Build deno and V8's d8. -ninja -C target/release d8 - -# Start the program we want to benchmark with --prof -./target/release/deno run tests/http_bench.ts --allow-net --v8-flags=--prof & - -# Exercise it. -third_party/wrk/linux/wrk http://localhost:4500/ -kill `pgrep deno` -``` - -V8 will write a file in the current directory that looks like this: -`isolate-0x7fad98242400-v8.log`. To examine this file: - -```sh -D8_PATH=target/release/ ./third_party/v8/tools/linux-tick-processor -isolate-0x7fad98242400-v8.log > prof.log -# on macOS, use ./third_party/v8/tools/mac-tick-processor instead -``` - -`prof.log` will contain information about tick distribution of different calls. - -To view the log with Web UI, generate JSON file of the log: - -```sh -D8_PATH=target/release/ ./third_party/v8/tools/linux-tick-processor -isolate-0x7fad98242400-v8.log --preprocess > prof.json -``` - -Open `third_party/v8/tools/profview/index.html` in your browser, and select -`prof.json` to view the distribution graphically. - -Useful V8 flags during profiling: - -- --prof -- --log-internal-timer-events -- --log-timer-events -- --track-gc -- --log-source-code -- --track-gc-object-stats - -To learn more about `d8` and profiling, check out the following links: - -- [https://v8.dev/docs/d8](https://v8.dev/docs/d8) -- [https://v8.dev/docs/profile](https://v8.dev/docs/profile) - -### Debugging with LLDB - -To debug the deno binary, we can use `rust-lldb`. It should come with `rustc` -and is a wrapper around LLDB. - -```shell -$ rust-lldb -- ./target/debug/deno run --allow-net tests/http_bench.ts -# On macOS, you might get warnings like -# `ImportError: cannot import name _remove_dead_weakref` -# In that case, use system python by setting PATH, e.g. -# PATH=/System/Library/Frameworks/Python.framework/Versions/2.7/bin:$PATH -(lldb) command script import "/Users/kevinqian/.rustup/toolchains/1.36.0-x86_64-apple-darwin/lib/rustlib/etc/lldb_rust_formatters.py" -(lldb) type summary add --no-value --python-function lldb_rust_formatters.print_val -x ".*" --category Rust -(lldb) type category enable Rust -(lldb) target create "../deno/target/debug/deno" -Current executable set to '../deno/target/debug/deno' (x86_64). -(lldb) settings set -- target.run-args "tests/http_bench.ts" "--allow-net" -(lldb) b op_start -(lldb) r -``` - -### V8 flags - -V8 has many many internal command-line flags: - -```shell -$ deno run --v8-flags=--help _ -SSE3=1 SSSE3=1 SSE4_1=1 SSE4_2=1 SAHF=1 AVX=1 FMA3=1 BMI1=1 BMI2=1 LZCNT=1 POPCNT=1 ATOM=0 -Synopsis: - shell [options] [--shell] [<file>...] - d8 [options] [-e <string>] [--shell] [[--module] <file>...] - - -e execute a string in V8 - --shell run an interactive JavaScript shell - --module execute a file as a JavaScript module - -Note: the --module option is implicitly enabled for *.mjs files. - -The following syntax for options is accepted (both '-' and '--' are ok): - --flag (bool flags only) - --no-flag (bool flags only) - --flag=value (non-bool flags only, no spaces around '=') - --flag value (non-bool flags only) - -- (captures all remaining args in JavaScript) - -Options: - --use-strict (enforce strict mode) - type: bool default: false - --es-staging (enable test-worthy harmony features (for internal use only)) - type: bool default: false - --harmony (enable all completed harmony features) - type: bool default: false - --harmony-shipping (enable all shipped harmony features) - type: bool default: true - --harmony-regexp-sequence (enable "RegExp Unicode sequence properties" (in progress)) - type: bool default: false - --harmony-weak-refs-with-cleanup-some (enable "harmony weak references with FinalizationRegistry.prototype.cleanupSome" (in progress)) - type: bool default: false - --harmony-regexp-match-indices (enable "harmony regexp match indices" (in progress)) - type: bool default: false - --harmony-top-level-await (enable "harmony top level await") - type: bool default: false - --harmony-namespace-exports (enable "harmony namespace exports (export * as foo from 'bar')") - type: bool default: true - --harmony-sharedarraybuffer (enable "harmony sharedarraybuffer") - type: bool default: true - --harmony-import-meta (enable "harmony import.meta property") - type: bool default: true - --harmony-dynamic-import (enable "harmony dynamic import") - type: bool default: true - --harmony-promise-all-settled (enable "harmony Promise.allSettled") - type: bool default: true - --harmony-promise-any (enable "harmony Promise.any") - type: bool default: true - --harmony-private-methods (enable "harmony private methods in class literals") - type: bool default: true - --harmony-weak-refs (enable "harmony weak references") - type: bool default: true - --harmony-string-replaceall (enable "harmony String.prototype.replaceAll") - type: bool default: true - --harmony-logical-assignment (enable "harmony logical assignment") - type: bool default: true - --lite-mode (enables trade-off of performance for memory savings) - type: bool default: false - --future (Implies all staged features that we want to ship in the not-too-far future) - type: bool default: false - --assert-types (generate runtime type assertions to test the typer) - type: bool default: false - --allocation-site-pretenuring (pretenure with allocation sites) - type: bool default: true - --page-promotion (promote pages based on utilization) - type: bool default: true - --always-promote-young-mc (always promote young objects during mark-compact) - type: bool default: true - --page-promotion-threshold (min percentage of live bytes on a page to enable fast evacuation) - type: int default: 70 - --trace-pretenuring (trace pretenuring decisions of HAllocate instructions) - type: bool default: false - --trace-pretenuring-statistics (trace allocation site pretenuring statistics) - type: bool default: false - --track-fields (track fields with only smi values) - type: bool default: true - --track-double-fields (track fields with double values) - type: bool default: true - --track-heap-object-fields (track fields with heap values) - type: bool default: true - --track-computed-fields (track computed boilerplate fields) - type: bool default: true - --track-field-types (track field types) - type: bool default: true - --trace-block-coverage (trace collected block coverage information) - type: bool default: false - --trace-protector-invalidation (trace protector cell invalidations) - type: bool default: false - --feedback-normalization (feed back normalization to constructors) - type: bool default: false - --enable-one-shot-optimization (Enable size optimizations for the code that will only be executed once) - type: bool default: false - --unbox-double-arrays (automatically unbox arrays of doubles) - type: bool default: true - --interrupt-budget (interrupt budget which should be used for the profiler counter) - type: int default: 147456 - --jitless (Disable runtime allocation of executable memory.) - type: bool default: false - --use-ic (use inline caching) - type: bool default: true - --budget-for-feedback-vector-allocation (The budget in amount of bytecode executed by a function before we decide to allocate feedback vectors) - type: int default: 1024 - --lazy-feedback-allocation (Allocate feedback vectors lazily) - type: bool default: true - --ignition-elide-noneffectful-bytecodes (elide bytecodes which won't have any external effect) - type: bool default: true - --ignition-reo (use ignition register equivalence optimizer) - type: bool default: true - --ignition-filter-expression-positions (filter expression positions before the bytecode pipeline) - type: bool default: true - --ignition-share-named-property-feedback (share feedback slots when loading the same named property from the same object) - type: bool default: true - --print-bytecode (print bytecode generated by ignition interpreter) - type: bool default: false - --enable-lazy-source-positions (skip generating source positions during initial compile but regenerate when actually required) - type: bool default: true - --stress-lazy-source-positions (collect lazy source positions immediately after lazy compile) - type: bool default: false - --print-bytecode-filter (filter for selecting which functions to print bytecode) - type: string default: * - --trace-ignition-codegen (trace the codegen of ignition interpreter bytecode handlers) - type: bool default: false - --trace-ignition-dispatches (traces the dispatches to bytecode handlers by the ignition interpreter) - type: bool default: false - --trace-ignition-dispatches-output-file (the file to which the bytecode handler dispatch table is written (by default, the table is not written to a file)) - type: string default: nullptr - --fast-math (faster (but maybe less accurate) math functions) - type: bool default: true - --trace-track-allocation-sites (trace the tracking of allocation sites) - type: bool default: false - --trace-migration (trace object migration) - type: bool default: false - --trace-generalization (trace map generalization) - type: bool default: false - --turboprop (enable experimental turboprop mid-tier compiler.) - type: bool default: false - --concurrent-recompilation (optimizing hot functions asynchronously on a separate thread) - type: bool default: true - --trace-concurrent-recompilation (track concurrent recompilation) - type: bool default: false - --concurrent-recompilation-queue-length (the length of the concurrent compilation queue) - type: int default: 8 - --concurrent-recompilation-delay (artificial compilation delay in ms) - type: int default: 0 - --block-concurrent-recompilation (block queued jobs until released) - type: bool default: false - --concurrent-inlining (run optimizing compiler's inlining phase on a separate thread) - type: bool default: false - --max-serializer-nesting (maximum levels for nesting child serializers) - type: int default: 25 - --trace-heap-broker-verbose (trace the heap broker verbosely (all reports)) - type: bool default: false - --trace-heap-broker-memory (trace the heap broker memory (refs analysis and zone numbers)) - type: bool default: false - --trace-heap-broker (trace the heap broker (reports on missing data only)) - type: bool default: false - --stress-runs (number of stress runs) - type: int default: 0 - --deopt-every-n-times (deoptimize every n times a deopt point is passed) - type: int default: 0 - --print-deopt-stress (print number of possible deopt points) - type: bool default: false - --opt (use adaptive optimizations) - type: bool default: true - --turbo-sp-frame-access (use stack pointer-relative access to frame wherever possible) - type: bool default: false - --turbo-control-flow-aware-allocation (consider control flow while allocating registers) - type: bool default: true - --turbo-filter (optimization filter for TurboFan compiler) - type: string default: * - --trace-turbo (trace generated TurboFan IR) - type: bool default: false - --trace-turbo-path (directory to dump generated TurboFan IR to) - type: string default: nullptr - --trace-turbo-filter (filter for tracing turbofan compilation) - type: string default: * - --trace-turbo-graph (trace generated TurboFan graphs) - type: bool default: false - --trace-turbo-scheduled (trace TurboFan IR with schedule) - type: bool default: false - --trace-turbo-cfg-file (trace turbo cfg graph (for C1 visualizer) to a given file name) - type: string default: nullptr - --trace-turbo-types (trace TurboFan's types) - type: bool default: true - --trace-turbo-scheduler (trace TurboFan's scheduler) - type: bool default: false - --trace-turbo-reduction (trace TurboFan's various reducers) - type: bool default: false - --trace-turbo-trimming (trace TurboFan's graph trimmer) - type: bool default: false - --trace-turbo-jt (trace TurboFan's jump threading) - type: bool default: false - --trace-turbo-ceq (trace TurboFan's control equivalence) - type: bool default: false - --trace-turbo-loop (trace TurboFan's loop optimizations) - type: bool default: false - --trace-turbo-alloc (trace TurboFan's register allocator) - type: bool default: false - --trace-all-uses (trace all use positions) - type: bool default: false - --trace-representation (trace representation types) - type: bool default: false - --turbo-verify (verify TurboFan graphs at each phase) - type: bool default: false - --turbo-verify-machine-graph (verify TurboFan machine graph before instruction selection) - type: string default: nullptr - --trace-verify-csa (trace code stubs verification) - type: bool default: false - --csa-trap-on-node (trigger break point when a node with given id is created in given stub. The format is: StubName,NodeId) - type: string default: nullptr - --turbo-stats (print TurboFan statistics) - type: bool default: false - --turbo-stats-nvp (print TurboFan statistics in machine-readable format) - type: bool default: false - --turbo-stats-wasm (print TurboFan statistics of wasm compilations) - type: bool default: false - --turbo-splitting (split nodes during scheduling in TurboFan) - type: bool default: true - --function-context-specialization (enable function context specialization in TurboFan) - type: bool default: false - --turbo-inlining (enable inlining in TurboFan) - type: bool default: true - --max-inlined-bytecode-size (maximum size of bytecode for a single inlining) - type: int default: 500 - --max-inlined-bytecode-size-cumulative (maximum cumulative size of bytecode considered for inlining) - type: int default: 1000 - --max-inlined-bytecode-size-absolute (maximum cumulative size of bytecode considered for inlining) - type: int default: 5000 - --reserve-inline-budget-scale-factor (maximum cumulative size of bytecode considered for inlining) - type: float default: 1.2 - --max-inlined-bytecode-size-small (maximum size of bytecode considered for small function inlining) - type: int default: 30 - --max-optimized-bytecode-size (maximum bytecode size to be considered for optimization; too high values may cause the compiler to hit (release) assertions) - type: int default: 61440 - --min-inlining-frequency (minimum frequency for inlining) - type: float default: 0.15 - --polymorphic-inlining (polymorphic inlining) - type: bool default: true - --stress-inline (set high thresholds for inlining to inline as much as possible) - type: bool default: false - --trace-turbo-inlining (trace TurboFan inlining) - type: bool default: false - --turbo-inline-array-builtins (inline array builtins in TurboFan code) - type: bool default: true - --use-osr (use on-stack replacement) - type: bool default: true - --trace-osr (trace on-stack replacement) - type: bool default: false - --analyze-environment-liveness (analyze liveness of environment slots and zap dead values) - type: bool default: true - --trace-environment-liveness (trace liveness of local variable slots) - type: bool default: false - --turbo-load-elimination (enable load elimination in TurboFan) - type: bool default: true - --trace-turbo-load-elimination (trace TurboFan load elimination) - type: bool default: false - --turbo-profiling (enable basic block profiling in TurboFan) - type: bool default: false - --turbo-profiling-verbose (enable basic block profiling in TurboFan, and include each function's schedule and disassembly in the output) - type: bool default: false - --turbo-verify-allocation (verify register allocation in TurboFan) - type: bool default: false - --turbo-move-optimization (optimize gap moves in TurboFan) - type: bool default: true - --turbo-jt (enable jump threading in TurboFan) - type: bool default: true - --turbo-loop-peeling (Turbofan loop peeling) - type: bool default: true - --turbo-loop-variable (Turbofan loop variable optimization) - type: bool default: true - --turbo-loop-rotation (Turbofan loop rotation) - type: bool default: true - --turbo-cf-optimization (optimize control flow in TurboFan) - type: bool default: true - --turbo-escape (enable escape analysis) - type: bool default: true - --turbo-allocation-folding (Turbofan allocation folding) - type: bool default: true - --turbo-instruction-scheduling (enable instruction scheduling in TurboFan) - type: bool default: false - --turbo-stress-instruction-scheduling (randomly schedule instructions to stress dependency tracking) - type: bool default: false - --turbo-store-elimination (enable store-store elimination in TurboFan) - type: bool default: true - --trace-store-elimination (trace store elimination) - type: bool default: false - --turbo-rewrite-far-jumps (rewrite far to near jumps (ia32,x64)) - type: bool default: true - --stress-gc-during-compilation (simulate GC/compiler thread race related to https://crbug.com/v8/8520) - type: bool default: false - --turbo-fast-api-calls (enable fast API calls from TurboFan) - type: bool default: false - --reuse-opt-code-count (don't discard optimized code for the specified number of deopts.) - type: int default: 0 - --turbo-nci (enable experimental native context independent code.) - type: bool default: false - --turbo-nci-as-highest-tier (replace default TF with NCI code as the highest tier for testing purposes.) - type: bool default: false - --print-nci-code (print native context independent code.) - type: bool default: false - --trace-turbo-nci (trace native context independent code.) - type: bool default: false - --turbo-collect-feedback-in-generic-lowering (enable experimental feedback collection in generic lowering.) - type: bool default: false - --optimize-for-size (Enables optimizations which favor memory size over execution speed) - type: bool default: false - --untrusted-code-mitigations (Enable mitigations for executing untrusted code) - type: bool default: false - --expose-wasm (expose wasm interface to JavaScript) - type: bool default: true - --assume-asmjs-origin (force wasm decoder to assume input is internal asm-wasm format) - type: bool default: false - --wasm-num-compilation-tasks (maximum number of parallel compilation tasks for wasm) - type: int default: 128 - --wasm-write-protect-code-memory (write protect code memory on the wasm native heap) - type: bool default: false - --wasm-async-compilation (enable actual asynchronous compilation for WebAssembly.compile) - type: bool default: true - --wasm-test-streaming (use streaming compilation instead of async compilation for tests) - type: bool default: false - --wasm-max-mem-pages (maximum initial number of 64KiB memory pages of a wasm instance) - type: uint default: 32767 - --wasm-max-mem-pages-growth (maximum number of 64KiB pages a Wasm memory can grow to) - type: uint default: 65536 - --wasm-max-table-size (maximum table size of a wasm instance) - type: uint default: 10000000 - --wasm-max-code-space (maximum committed code space for wasm (in MB)) - type: uint default: 1024 - --wasm-tier-up (enable tier up to the optimizing compiler (requires --liftoff to have an effect)) - type: bool default: true - --trace-wasm-ast-start (start function for wasm AST trace (inclusive)) - type: int default: 0 - --trace-wasm-ast-end (end function for wasm AST trace (exclusive)) - type: int default: 0 - --liftoff (enable Liftoff, the baseline compiler for WebAssembly) - type: bool default: true - --trace-wasm-memory (print all memory updates performed in wasm code) - type: bool default: false - --wasm-tier-mask-for-testing (bitmask of functions to compile with TurboFan instead of Liftoff) - type: int default: 0 - --wasm-expose-debug-eval (Expose wasm evaluator support on the CDP) - type: bool default: false - --validate-asm (validate asm.js modules before compiling) - type: bool default: true - --suppress-asm-messages (don't emit asm.js related messages (for golden file testing)) - type: bool default: false - --trace-asm-time (log asm.js timing info to the console) - type: bool default: false - --trace-asm-scanner (log tokens encountered by asm.js scanner) - type: bool default: false - --trace-asm-parser (verbose logging of asm.js parse failures) - type: bool default: false - --stress-validate-asm (try to validate everything as asm.js) - type: bool default: false - --dump-wasm-module-path (directory to dump wasm modules to) - type: string default: nullptr - --experimental-wasm-eh (enable prototype exception handling opcodes for wasm) - type: bool default: false - --experimental-wasm-simd (enable prototype SIMD opcodes for wasm) - type: bool default: false - --experimental-wasm-return-call (enable prototype return call opcodes for wasm) - type: bool default: false - --experimental-wasm-compilation-hints (enable prototype compilation hints section for wasm) - type: bool default: false - --experimental-wasm-gc (enable prototype garbage collection for wasm) - type: bool default: false - --experimental-wasm-typed-funcref (enable prototype typed function references for wasm) - type: bool default: false - --experimental-wasm-reftypes (enable prototype reference type opcodes for wasm) - type: bool default: false - --experimental-wasm-threads (enable prototype thread opcodes for wasm) - type: bool default: false - --experimental-wasm-type-reflection (enable prototype wasm type reflection in JS for wasm) - type: bool default: false - --experimental-wasm-bigint (enable prototype JS BigInt support for wasm) - type: bool default: true - --experimental-wasm-bulk-memory (enable prototype bulk memory opcodes for wasm) - type: bool default: true - --experimental-wasm-mv (enable prototype multi-value support for wasm) - type: bool default: true - --wasm-staging (enable staged wasm features) - type: bool default: false - --wasm-opt (enable wasm optimization) - type: bool default: false - --wasm-bounds-checks (enable bounds checks (disable for performance testing only)) - type: bool default: true - --wasm-stack-checks (enable stack checks (disable for performance testing only)) - type: bool default: true - --wasm-math-intrinsics (intrinsify some Math imports into wasm) - type: bool default: true - --wasm-trap-handler (use signal handlers to catch out of bounds memory access in wasm (currently Linux x86_64 only)) - type: bool default: true - --wasm-fuzzer-gen-test (generate a test case when running a wasm fuzzer) - type: bool default: false - --print-wasm-code (Print WebAssembly code) - type: bool default: false - --print-wasm-stub-code (Print WebAssembly stub code) - type: bool default: false - --asm-wasm-lazy-compilation (enable lazy compilation for asm-wasm modules) - type: bool default: false - --wasm-lazy-compilation (enable lazy compilation for all wasm modules) - type: bool default: false - --wasm-lazy-validation (enable lazy validation for lazily compiled wasm functions) - type: bool default: false - --wasm-atomics-on-non-shared-memory (allow atomic operations on non-shared WebAssembly memory) - type: bool default: true - --wasm-grow-shared-memory (allow growing shared WebAssembly memory objects) - type: bool default: true - --wasm-simd-post-mvp (allow experimental SIMD operations for prototyping that are not included in the current proposal) - type: bool default: false - --wasm-code-gc (enable garbage collection of wasm code) - type: bool default: true - --trace-wasm-code-gc (trace garbage collection of wasm code) - type: bool default: false - --stress-wasm-code-gc (stress test garbage collection of wasm code) - type: bool default: false - --wasm-max-initial-code-space-reservation (maximum size of the initial wasm code space reservation (in MB)) - type: int default: 0 - --frame-count (number of stack frames inspected by the profiler) - type: int default: 1 - --stress-sampling-allocation-profiler (Enables sampling allocation profiler with X as a sample interval) - type: int default: 0 - --lazy-new-space-shrinking (Enables the lazy new space shrinking strategy) - type: bool default: false - --min-semi-space-size (min size of a semi-space (in MBytes), the new space consists of two semi-spaces) - type: size_t default: 0 - --max-semi-space-size (max size of a semi-space (in MBytes), the new space consists of two semi-spaces) - type: size_t default: 0 - --semi-space-growth-factor (factor by which to grow the new space) - type: int default: 2 - --max-old-space-size (max size of the old space (in Mbytes)) - type: size_t default: 0 - --max-heap-size (max size of the heap (in Mbytes) both max_semi_space_size and max_old_space_size take precedence. All three flags cannot be specified at the same time.) - type: size_t default: 0 - --initial-heap-size (initial size of the heap (in Mbytes)) - type: size_t default: 0 - --huge-max-old-generation-size (Increase max size of the old space to 4 GB for x64 systems withthe physical memory bigger than 16 GB) - type: bool default: true - --initial-old-space-size (initial old space size (in Mbytes)) - type: size_t default: 0 - --global-gc-scheduling (enable GC scheduling based on global memory) - type: bool default: true - --gc-global (always perform global GCs) - type: bool default: false - --random-gc-interval (Collect garbage after random(0, X) allocations. It overrides gc_interval.) - type: int default: 0 - --gc-interval (garbage collect after <n> allocations) - type: int default: -1 - --retain-maps-for-n-gc (keeps maps alive for <n> old space garbage collections) - type: int default: 2 - --trace-gc (print one trace line following each garbage collection) - type: bool default: false - --trace-gc-nvp (print one detailed trace line in name=value format after each garbage collection) - type: bool default: false - --trace-gc-ignore-scavenger (do not print trace line after scavenger collection) - type: bool default: false - --trace-idle-notification (print one trace line following each idle notification) - type: bool default: false - --trace-idle-notification-verbose (prints the heap state used by the idle notification) - type: bool default: false - --trace-gc-verbose (print more details following each garbage collection) - type: bool default: false - --trace-gc-freelists (prints details of each freelist before and after each major garbage collection) - type: bool default: false - --trace-gc-freelists-verbose (prints details of freelists of each page before and after each major garbage collection) - type: bool default: false - --trace-evacuation-candidates (Show statistics about the pages evacuation by the compaction) - type: bool default: false - --trace-allocations-origins (Show statistics about the origins of allocations. Combine with --no-inline-new to track allocations from generated code) - type: bool default: false - --trace-allocation-stack-interval (print stack trace after <n> free-list allocations) - type: int default: -1 - --trace-duplicate-threshold-kb (print duplicate objects in the heap if their size is more than given threshold) - type: int default: 0 - --trace-fragmentation (report fragmentation for old space) - type: bool default: false - --trace-fragmentation-verbose (report fragmentation for old space (detailed)) - type: bool default: false - --minor-mc-trace-fragmentation (trace fragmentation after marking) - type: bool default: false - --trace-evacuation (report evacuation statistics) - type: bool default: false - --trace-mutator-utilization (print mutator utilization, allocation speed, gc speed) - type: bool default: false - --incremental-marking (use incremental marking) - type: bool default: true - --incremental-marking-wrappers (use incremental marking for marking wrappers) - type: bool default: true - --incremental-marking-task (use tasks for incremental marking) - type: bool default: true - --incremental-marking-soft-trigger (threshold for starting incremental marking via a task in percent of available space: limit - size) - type: int default: 0 - --incremental-marking-hard-trigger (threshold for starting incremental marking immediately in percent of available space: limit - size) - type: int default: 0 - --trace-unmapper (Trace the unmapping) - type: bool default: false - --parallel-scavenge (parallel scavenge) - type: bool default: true - --scavenge-task (schedule scavenge tasks) - type: bool default: true - --scavenge-task-trigger (scavenge task trigger in percent of the current heap limit) - type: int default: 80 - --scavenge-separate-stack-scanning (use a separate phase for stack scanning in scavenge) - type: bool default: false - --trace-parallel-scavenge (trace parallel scavenge) - type: bool default: false - --write-protect-code-memory (write protect code memory) - type: bool default: true - --concurrent-marking (use concurrent marking) - type: bool default: true - --concurrent-array-buffer-sweeping (concurrently sweep array buffers) - type: bool default: true - --concurrent-allocation (concurrently allocate in old space) - type: bool default: false - --local-heaps (allow heap access from background tasks) - type: bool default: false - --stress-concurrent-allocation (start background threads that allocate memory) - type: bool default: false - --parallel-marking (use parallel marking in atomic pause) - type: bool default: true - --ephemeron-fixpoint-iterations (number of fixpoint iterations it takes to switch to linear ephemeron algorithm) - type: int default: 10 - --trace-concurrent-marking (trace concurrent marking) - type: bool default: false - --concurrent-store-buffer (use concurrent store buffer processing) - type: bool default: true - --concurrent-sweeping (use concurrent sweeping) - type: bool default: true - --parallel-compaction (use parallel compaction) - type: bool default: true - --parallel-pointer-update (use parallel pointer update during compaction) - type: bool default: true - --detect-ineffective-gcs-near-heap-limit (trigger out-of-memory failure to avoid GC storm near heap limit) - type: bool default: true - --trace-incremental-marking (trace progress of the incremental marking) - type: bool default: false - --trace-stress-marking (trace stress marking progress) - type: bool default: false - --trace-stress-scavenge (trace stress scavenge progress) - type: bool default: false - --track-gc-object-stats (track object counts and memory usage) - type: bool default: false - --trace-gc-object-stats (trace object counts and memory usage) - type: bool default: false - --trace-zone-stats (trace zone memory usage) - type: bool default: false - --zone-stats-tolerance (report a tick only when allocated zone memory changes by this amount) - type: size_t default: 1048576 - --track-retaining-path (enable support for tracking retaining path) - type: bool default: false - --concurrent-array-buffer-freeing (free array buffer allocations on a background thread) - type: bool default: true - --gc-stats (Used by tracing internally to enable gc statistics) - type: int default: 0 - --track-detached-contexts (track native contexts that are expected to be garbage collected) - type: bool default: true - --trace-detached-contexts (trace native contexts that are expected to be garbage collected) - type: bool default: false - --move-object-start (enable moving of object starts) - type: bool default: true - --memory-reducer (use memory reducer) - type: bool default: true - --memory-reducer-for-small-heaps (use memory reducer for small heaps) - type: bool default: true - --heap-growing-percent (specifies heap growing factor as (1 + heap_growing_percent/100)) - type: int default: 0 - --v8-os-page-size (override OS page size (in KBytes)) - type: int default: 0 - --always-compact (Perform compaction on every full GC) - type: bool default: false - --never-compact (Never perform compaction on full GC - testing only) - type: bool default: false - --compact-code-space (Compact code space on full collections) - type: bool default: true - --flush-bytecode (flush of bytecode when it has not been executed recently) - type: bool default: true - --stress-flush-bytecode (stress bytecode flushing) - type: bool default: false - --use-marking-progress-bar (Use a progress bar to scan large objects in increments when incremental marking is active.) - type: bool default: true - --stress-per-context-marking-worklist (Use per-context worklist for marking) - type: bool default: false - --force-marking-deque-overflows (force overflows of marking deque by reducing it's size to 64 words) - type: bool default: false - --stress-compaction (stress the GC compactor to flush out bugs (implies --force_marking_deque_overflows)) - type: bool default: false - --stress-compaction-random (Stress GC compaction by selecting random percent of pages as evacuation candidates. It overrides stress_compaction.) - type: bool default: false - --stress-incremental-marking (force incremental marking for small heaps and run it more often) - type: bool default: false - --fuzzer-gc-analysis (prints number of allocations and enables analysis mode for gc fuzz testing, e.g. --stress-marking, --stress-scavenge) - type: bool default: false - --stress-marking (force marking at random points between 0 and X (inclusive) percent of the regular marking start limit) - type: int default: 0 - --stress-scavenge (force scavenge at random points between 0 and X (inclusive) percent of the new space capacity) - type: int default: 0 - --gc-experiment-background-schedule (new background GC schedule heuristics) - type: bool default: false - --gc-experiment-less-compaction (less compaction in non-memory reducing mode) - type: bool default: false - --disable-abortjs (disables AbortJS runtime function) - type: bool default: false - --randomize-all-allocations (randomize virtual memory reservations by ignoring any hints passed when allocating pages) - type: bool default: false - --manual-evacuation-candidates-selection (Test mode only flag. It allows an unit test to select evacuation candidates pages (requires --stress_compaction).) - type: bool default: false - --fast-promotion-new-space (fast promote new space on high survival rates) - type: bool default: false - --clear-free-memory (initialize free memory with 0) - type: bool default: false - --young-generation-large-objects (allocates large objects by default in the young generation large object space) - type: bool default: true - --debug-code (generate extra code (assertions) for debugging) - type: bool default: false - --code-comments (emit comments in code disassembly; for more readable source positions you should add --no-concurrent_recompilation) - type: bool default: false - --enable-sse3 (enable use of SSE3 instructions if available) - type: bool default: true - --enable-ssse3 (enable use of SSSE3 instructions if available) - type: bool default: true - --enable-sse4-1 (enable use of SSE4.1 instructions if available) - type: bool default: true - --enable-sse4-2 (enable use of SSE4.2 instructions if available) - type: bool default: true - --enable-sahf (enable use of SAHF instruction if available (X64 only)) - type: bool default: true - --enable-avx (enable use of AVX instructions if available) - type: bool default: true - --enable-fma3 (enable use of FMA3 instructions if available) - type: bool default: true - --enable-bmi1 (enable use of BMI1 instructions if available) - type: bool default: true - --enable-bmi2 (enable use of BMI2 instructions if available) - type: bool default: true - --enable-lzcnt (enable use of LZCNT instruction if available) - type: bool default: true - --enable-popcnt (enable use of POPCNT instruction if available) - type: bool default: true - --arm-arch (generate instructions for the selected ARM architecture if available: armv6, armv7, armv7+sudiv or armv8) - type: string default: armv8 - --force-long-branches (force all emitted branches to be in long mode (MIPS/PPC only)) - type: bool default: false - --mcpu (enable optimization for specific cpu) - type: string default: auto - --partial-constant-pool (enable use of partial constant pools (X64 only)) - type: bool default: true - --sim-arm64-optional-features (enable optional features on the simulator for testing: none or all) - type: string default: none - --enable-source-at-csa-bind (Include source information in the binary at CSA bind locations.) - type: bool default: false - --enable-armv7 (deprecated (use --arm_arch instead)) - type: maybe_bool default: unset - --enable-vfp3 (deprecated (use --arm_arch instead)) - type: maybe_bool default: unset - --enable-32dregs (deprecated (use --arm_arch instead)) - type: maybe_bool default: unset - --enable-neon (deprecated (use --arm_arch instead)) - type: maybe_bool default: unset - --enable-sudiv (deprecated (use --arm_arch instead)) - type: maybe_bool default: unset - --enable-armv8 (deprecated (use --arm_arch instead)) - type: maybe_bool default: unset - --enable-regexp-unaligned-accesses (enable unaligned accesses for the regexp engine) - type: bool default: true - --script-streaming (enable parsing on background) - type: bool default: true - --stress-background-compile (stress test parsing on background) - type: bool default: false - --finalize-streaming-on-background (perform the script streaming finalization on the background thread) - type: bool default: false - --disable-old-api-accessors (Disable old-style API accessors whose setters trigger through the prototype chain) - type: bool default: false - --expose-gc (expose gc extension) - type: bool default: false - --expose-gc-as (expose gc extension under the specified name) - type: string default: nullptr - --expose-externalize-string (expose externalize string extension) - type: bool default: false - --expose-trigger-failure (expose trigger-failure extension) - type: bool default: false - --stack-trace-limit (number of stack frames to capture) - type: int default: 10 - --builtins-in-stack-traces (show built-in functions in stack traces) - type: bool default: false - --experimental-stack-trace-frames (enable experimental frames (API/Builtins) and stack trace layout) - type: bool default: false - --disallow-code-generation-from-strings (disallow eval and friends) - type: bool default: false - --expose-async-hooks (expose async_hooks object) - type: bool default: false - --expose-cputracemark-as (expose cputracemark extension under the specified name) - type: string default: nullptr - --allow-unsafe-function-constructor (allow invoking the function constructor without security checks) - type: bool default: false - --force-slow-path (always take the slow path for builtins) - type: bool default: false - --test-small-max-function-context-stub-size (enable testing the function context size overflow path by making the maximum size smaller) - type: bool default: false - --inline-new (use fast inline allocation) - type: bool default: true - --trace (trace javascript function calls) - type: bool default: false - --trace-wasm (trace wasm function calls) - type: bool default: false - --lazy (use lazy compilation) - type: bool default: true - --max-lazy (ignore eager compilation hints) - type: bool default: false - --trace-opt (trace lazy optimization) - type: bool default: false - --trace-opt-verbose (extra verbose compilation tracing) - type: bool default: false - --trace-opt-stats (trace lazy optimization statistics) - type: bool default: false - --trace-deopt (trace optimize function deoptimization) - type: bool default: false - --trace-file-names (include file names in trace-opt/trace-deopt output) - type: bool default: false - --always-opt (always try to optimize functions) - type: bool default: false - --always-osr (always try to OSR functions) - type: bool default: false - --prepare-always-opt (prepare for turning on always opt) - type: bool default: false - --trace-serializer (print code serializer trace) - type: bool default: false - --compilation-cache (enable compilation cache) - type: bool default: true - --cache-prototype-transitions (cache prototype transitions) - type: bool default: true - --parallel-compile-tasks (enable parallel compile tasks) - type: bool default: false - --compiler-dispatcher (enable compiler dispatcher) - type: bool default: false - --trace-compiler-dispatcher (trace compiler dispatcher activity) - type: bool default: false - --cpu-profiler-sampling-interval (CPU profiler sampling interval in microseconds) - type: int default: 1000 - --trace-side-effect-free-debug-evaluate (print debug messages for side-effect-free debug-evaluate for testing) - type: bool default: false - --hard-abort (abort by crashing) - type: bool default: true - --expose-inspector-scripts (expose injected-script-source.js for debugging) - type: bool default: false - --stack-size (default size of stack region v8 is allowed to use (in kBytes)) - type: int default: 984 - --max-stack-trace-source-length (maximum length of function source code printed in a stack trace.) - type: int default: 300 - --clear-exceptions-on-js-entry (clear pending exceptions when entering JavaScript) - type: bool default: false - --histogram-interval (time interval in ms for aggregating memory histograms) - type: int default: 600000 - --heap-profiler-trace-objects (Dump heap object allocations/movements/size_updates) - type: bool default: false - --heap-profiler-use-embedder-graph (Use the new EmbedderGraph API to get embedder nodes) - type: bool default: true - --heap-snapshot-string-limit (truncate strings to this length in the heap snapshot) - type: int default: 1024 - --sampling-heap-profiler-suppress-randomness (Use constant sample intervals to eliminate test flakiness) - type: bool default: false - --use-idle-notification (Use idle notification to reduce memory footprint.) - type: bool default: true - --trace-ic (trace inline cache state transitions for tools/ic-processor) - type: bool default: false - --modify-field-representation-inplace (enable in-place field representation updates) - type: bool default: true - --max-polymorphic-map-count (maximum number of maps to track in POLYMORPHIC state) - type: int default: 4 - --native-code-counters (generate extra code for manipulating stats counters) - type: bool default: false - --thin-strings (Enable ThinString support) - type: bool default: true - --trace-prototype-users (Trace updates to prototype user tracking) - type: bool default: false - --trace-for-in-enumerate (Trace for-in enumerate slow-paths) - type: bool default: false - --trace-maps (trace map creation) - type: bool default: false - --trace-maps-details (also log map details) - type: bool default: true - --allow-natives-syntax (allow natives syntax) - type: bool default: false - --allow-natives-for-differential-fuzzing (allow only natives explicitly allowlisted for differential fuzzers) - type: bool default: false - --parse-only (only parse the sources) - type: bool default: false - --trace-sim (Trace simulator execution) - type: bool default: false - --debug-sim (Enable debugging the simulator) - type: bool default: false - --check-icache (Check icache flushes in ARM and MIPS simulator) - type: bool default: false - --stop-sim-at (Simulator stop after x number of instructions) - type: int default: 0 - --sim-stack-alignment (Stack alingment in bytes in simulator (4 or 8, 8 is default)) - type: int default: 8 - --sim-stack-size (Stack size of the ARM64, MIPS64 and PPC64 simulator in kBytes (default is 2 MB)) - type: int default: 2048 - --log-colour (When logging, try to use coloured output.) - type: bool default: true - --trace-sim-messages (Trace simulator debug messages. Implied by --trace-sim.) - type: bool default: false - --async-stack-traces (include async stack traces in Error.stack) - type: bool default: true - --stack-trace-on-illegal (print stack trace when an illegal exception is thrown) - type: bool default: false - --abort-on-uncaught-exception (abort program (dump core) when an uncaught exception is thrown) - type: bool default: false - --correctness-fuzzer-suppressions (Suppress certain unspecified behaviors to ease correctness fuzzing: Abort program when the stack overflows or a string exceeds maximum length (as opposed to throwing RangeError). Use a fixed suppression string for error messages.) - type: bool default: false - --randomize-hashes (randomize hashes to avoid predictable hash collisions (with snapshots this option cannot override the baked-in seed)) - type: bool default: true - --rehash-snapshot (rehash strings from the snapshot to override the baked-in seed) - type: bool default: true - --hash-seed (Fixed seed to use to hash property keys (0 means random)(with snapshots this option cannot override the baked-in seed)) - type: uint64 default: 0 - --random-seed (Default seed for initializing random generator (0, the default, means to use system random).) - type: int default: 0 - --fuzzer-random-seed (Default seed for initializing fuzzer random generator (0, the default, means to use v8's random number generator seed).) - type: int default: 0 - --trace-rail (trace RAIL mode) - type: bool default: false - --print-all-exceptions (print exception object and stack trace on each thrown exception) - type: bool default: false - --detailed-error-stack-trace (includes arguments for each function call in the error stack frames array) - type: bool default: false - --adjust-os-scheduling-parameters (adjust OS specific scheduling params for the isolate) - type: bool default: true - --runtime-call-stats (report runtime call counts and times) - type: bool default: false - --rcs (report runtime call counts and times) - type: bool default: false - --rcs-cpu-time (report runtime times in cpu time (the default is wall time)) - type: bool default: false - --profile-deserialization (Print the time it takes to deserialize the snapshot.) - type: bool default: false - --serialization-statistics (Collect statistics on serialized objects.) - type: bool default: false - --serialization-chunk-size (Custom size for serialization chunks) - type: uint default: 4096 - --regexp-optimization (generate optimized regexp code) - type: bool default: true - --regexp-mode-modifiers (enable inline flags in regexp.) - type: bool default: false - --regexp-interpret-all (interpret all regexp code) - type: bool default: false - --regexp-tier-up (enable regexp interpreter and tier up to the compiler after the number of executions set by the tier up ticks flag) - type: bool default: true - --regexp-tier-up-ticks (set the number of executions for the regexp interpreter before tiering-up to the compiler) - type: int default: 1 - --regexp-peephole-optimization (enable peephole optimization for regexp bytecode) - type: bool default: true - --trace-regexp-peephole-optimization (trace regexp bytecode peephole optimization) - type: bool default: false - --trace-regexp-bytecodes (trace regexp bytecode execution) - type: bool default: false - --trace-regexp-assembler (trace regexp macro assembler calls.) - type: bool default: false - --trace-regexp-parser (trace regexp parsing) - type: bool default: false - --trace-regexp-tier-up (trace regexp tiering up execution) - type: bool default: false - --testing-bool-flag (testing_bool_flag) - type: bool default: true - --testing-maybe-bool-flag (testing_maybe_bool_flag) - type: maybe_bool default: unset - --testing-int-flag (testing_int_flag) - type: int default: 13 - --testing-float-flag (float-flag) - type: float default: 2.5 - --testing-string-flag (string-flag) - type: string default: Hello, world! - --testing-prng-seed (Seed used for threading test randomness) - type: int default: 42 - --testing-d8-test-runner (test runner turns on this flag to enable a check that the function was prepared for optimization before marking it for optimization) - type: bool default: false - --fuzzing (Fuzzers use this flag to signal that they are ... fuzzing. This causes intrinsics to fail silently (e.g. return undefined) on invalid usage.) - type: bool default: false - --embedded-src (Path for the generated embedded data file. (mksnapshot only)) - type: string default: nullptr - --embedded-variant (Label to disambiguate symbols in embedded data file. (mksnapshot only)) - type: string default: nullptr - --startup-src (Write V8 startup as C++ src. (mksnapshot only)) - type: string default: nullptr - --startup-blob (Write V8 startup blob file. (mksnapshot only)) - type: string default: nullptr - --target-arch (The mksnapshot target arch. (mksnapshot only)) - type: string default: nullptr - --target-os (The mksnapshot target os. (mksnapshot only)) - type: string default: nullptr - --target-is-simulator (Instruct mksnapshot that the target is meant to run in the simulator and it can generate simulator-specific instructions. (mksnapshot only)) - type: bool default: false - --minor-mc-parallel-marking (use parallel marking for the young generation) - type: bool default: true - --trace-minor-mc-parallel-marking (trace parallel marking for the young generation) - type: bool default: false - --minor-mc (perform young generation mark compact GCs) - type: bool default: false - --help (Print usage message, including flags, on console) - type: bool default: true - --dump-counters (Dump counters on exit) - type: bool default: false - --dump-counters-nvp (Dump counters as name-value pairs on exit) - type: bool default: false - --use-external-strings (Use external strings for source code) - type: bool default: false - --map-counters (Map counters to a file) - type: string default: - --mock-arraybuffer-allocator (Use a mock ArrayBuffer allocator for testing.) - type: bool default: false - --mock-arraybuffer-allocator-limit (Memory limit for mock ArrayBuffer allocator used to simulate OOM for testing.) - type: size_t default: 0 - --gdbjit (enable GDBJIT interface) - type: bool default: false - --gdbjit-full (enable GDBJIT interface for all code objects) - type: bool default: false - --gdbjit-dump (dump elf objects with debug info to disk) - type: bool default: false - --gdbjit-dump-filter (dump only objects containing this substring) - type: string default: - --log (Minimal logging (no API, code, GC, suspect, or handles samples).) - type: bool default: false - --log-all (Log all events to the log file.) - type: bool default: false - --log-api (Log API events to the log file.) - type: bool default: false - --log-code (Log code events to the log file without profiling.) - type: bool default: false - --log-handles (Log global handle events.) - type: bool default: false - --log-suspect (Log suspect operations.) - type: bool default: false - --log-source-code (Log source code.) - type: bool default: false - --log-function-events (Log function events (parse, compile, execute) separately.) - type: bool default: false - --prof (Log statistical profiling information (implies --log-code).) - type: bool default: false - --detailed-line-info (Always generate detailed line information for CPU profiling.) - type: bool default: false - --prof-sampling-interval (Interval for --prof samples (in microseconds).) - type: int default: 1000 - --prof-cpp (Like --prof, but ignore generated code.) - type: bool default: false - --prof-browser-mode (Used with --prof, turns on browser-compatible mode for profiling.) - type: bool default: true - --logfile (Specify the name of the log file.) - type: string default: v8.log - --logfile-per-isolate (Separate log files for each isolate.) - type: bool default: true - --ll-prof (Enable low-level linux profiler.) - type: bool default: false - --gc-fake-mmap (Specify the name of the file for fake gc mmap used in ll_prof) - type: string default: /tmp/__v8_gc__ - --log-internal-timer-events (Time internal events.) - type: bool default: false - --redirect-code-traces (output deopt information and disassembly into file code-<pid>-<isolate id>.asm) - type: bool default: false - --redirect-code-traces-to (output deopt information and disassembly into the given file) - type: string default: nullptr - --print-opt-source (print source code of optimized and inlined functions) - type: bool default: false - --vtune-prof-annotate-wasm (Used when v8_enable_vtunejit is enabled, load wasm source map and provide annotate support (experimental).) - type: bool default: false - --win64-unwinding-info (Enable unwinding info for Windows/x64) - type: bool default: true - --interpreted-frames-native-stack (Show interpreted frames on the native stack (useful for external profilers).) - type: bool default: false - --predictable (enable predictable mode) - type: bool default: false - --predictable-gc-schedule (Predictable garbage collection schedule. Fixes heap growing, idle, and memory reducing behavior.) - type: bool default: false - --single-threaded (disable the use of background tasks) - type: bool default: false - --single-threaded-gc (disable the use of background gc tasks) - type: bool default: false -``` - -Particularly useful ones: - -``` ---async-stack-trace -``` - ### Continuous Benchmarks See our benchmarks [over here](https://deno.land/benchmarks) |