perf: disable snapshot compression (#18061)

This commit disables snapshot compression for the CLI snapshot.]

Decompressing the snapshot on startup takes ~2.5ms.

4 files changed, 7 insertions, 75 deletions

diff --git a/cli/build.rs b/cli/build.rs
index 9d133d99a..c0a22ba12 100644
--- a/cli/build.rs
+++ b/cli/build.rs
@@ -380,14 +380,7 @@ fn create_cli_snapshot(snapshot_path: PathBuf) {
     startup_snapshot: Some(deno_runtime::js::deno_isolate_init()),
     extensions,
     extensions_with_js,
-    compression_cb: Some(Box::new(|vec, snapshot_slice| {
-      lzzzz::lz4_hc::compress_to_vec(
-        snapshot_slice,
-        vec,
-        lzzzz::lz4_hc::CLEVEL_MAX,
-      )
-      .expect("snapshot compression failed");
-    })),
+    compression_cb: None,
     snapshot_module_load_cb: None,
   })
 }
diff --git a/cli/js.rs b/cli/js.rs
index 06a6a5fd9..f3c4fea68 100644
--- a/cli/js.rs
+++ b/cli/js.rs
@@ -1,37 +1,12 @@
 // Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
 
 use deno_core::Snapshot;
-use log::debug;
-use once_cell::sync::Lazy;
 
-pub static CLI_SNAPSHOT: Lazy<Box<[u8]>> = Lazy::new(
-  #[allow(clippy::uninit_vec)]
-  #[cold]
-  #[inline(never)]
-  || {
-    static COMPRESSED_CLI_SNAPSHOT: &[u8] =
-      include_bytes!(concat!(env!("OUT_DIR"), "/CLI_SNAPSHOT.bin"));
-
-    let size =
-      u32::from_le_bytes(COMPRESSED_CLI_SNAPSHOT[0..4].try_into().unwrap())
-        as usize;
-    let mut vec = Vec::with_capacity(size);
-
-    // SAFETY: vec is allocated with exact snapshot size (+ alignment)
-    // SAFETY: non zeroed bytes are overwritten with decompressed snapshot
-    unsafe {
-      vec.set_len(size);
-    }
-
-    lzzzz::lz4::decompress(&COMPRESSED_CLI_SNAPSHOT[4..], &mut vec).unwrap();
-
-    vec.into_boxed_slice()
-  },
-);
+static CLI_SNAPSHOT: &[u8] =
+  include_bytes!(concat!(env!("OUT_DIR"), "/CLI_SNAPSHOT.bin"));
 
 pub fn deno_isolate_init() -> Snapshot {
-  debug!("Deno isolate init with snapshots.");
-  Snapshot::Static(&CLI_SNAPSHOT)
+  Snapshot::Static(CLI_SNAPSHOT)
 }
 
 #[cfg(test)]
diff --git a/runtime/build.rs b/runtime/build.rs
index 166421586..6da7ec419 100644
--- a/runtime/build.rs
+++ b/runtime/build.rs
@@ -294,14 +294,7 @@ mod startup_snapshot {
       startup_snapshot: None,
       extensions: vec![],
       extensions_with_js,
-      compression_cb: Some(Box::new(|vec, snapshot_slice| {
-        lzzzz::lz4_hc::compress_to_vec(
-          snapshot_slice,
-          vec,
-          lzzzz::lz4_hc::CLEVEL_MAX,
-        )
-        .expect("snapshot compression failed");
-      })),
+      compression_cb: None,
       snapshot_module_load_cb: Some(Box::new(transpile_ts_for_snapshotting)),
     });
   }
diff --git a/runtime/js.rs b/runtime/js.rs
index 57b1e7be4..3101e4b6b 100644
--- a/runtime/js.rs
+++ b/runtime/js.rs
@@ -1,43 +1,14 @@
 // Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
 #[cfg(not(feature = "dont_create_runtime_snapshot"))]
 use deno_core::Snapshot;
-#[cfg(not(feature = "dont_create_runtime_snapshot"))]
-use log::debug;
-#[cfg(not(feature = "dont_create_runtime_snapshot"))]
-use once_cell::sync::Lazy;
 
 #[cfg(not(feature = "dont_create_runtime_snapshot"))]
-static COMPRESSED_RUNTIME_SNAPSHOT: &[u8] =
+static RUNTIME_SNAPSHOT: &[u8] =
   include_bytes!(concat!(env!("OUT_DIR"), "/RUNTIME_SNAPSHOT.bin"));
 
 #[cfg(not(feature = "dont_create_runtime_snapshot"))]
-pub static RUNTIME_SNAPSHOT: Lazy<Box<[u8]>> = Lazy::new(
-  #[allow(clippy::uninit_vec)]
-  #[cold]
-  #[inline(never)]
-  || {
-    let size =
-      u32::from_le_bytes(COMPRESSED_RUNTIME_SNAPSHOT[0..4].try_into().unwrap())
-        as usize;
-    let mut vec = Vec::with_capacity(size);
-
-    // SAFETY: vec is allocated with exact snapshot size (+ alignment)
-    // SAFETY: non zeroed bytes are overwritten with decompressed snapshot
-    unsafe {
-      vec.set_len(size);
-    }
-
-    lzzzz::lz4::decompress(&COMPRESSED_RUNTIME_SNAPSHOT[4..], &mut vec)
-      .unwrap();
-
-    vec.into_boxed_slice()
-  },
-);
-
-#[cfg(not(feature = "dont_create_runtime_snapshot"))]
 pub fn deno_isolate_init() -> Snapshot {
-  debug!("Deno isolate init with snapshots.");
-  Snapshot::Static(&RUNTIME_SNAPSHOT)
+  Snapshot::Static(RUNTIME_SNAPSHOT)
 }
 
 #[cfg(not(feature = "include_js_files_for_snapshotting"))]