Attachment 341529 Details for Bug 186064 – patch

[patch] patch

b-backup.diff (text/plain), 3.59 KB, created by Saam Barati on 2018-05-29 15:32:31 PDT

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Creator: Saam Barati

Created: 2018-05-29 15:32:31 PDT

Size: 3.59 KB

patch

obsolete

>Index: Source/JavaScriptCore/ChangeLog
>===================================================================
>--- Source/JavaScriptCore/ChangeLog	(revision 232275)
>+++ Source/JavaScriptCore/ChangeLog	(working copy)
>@@ -1,3 +1,31 @@
>+2018-05-29  Saam Barati  <sbarati@apple.com>
>+
>+        JSVirtualMachine shrinkFootprint should run when the VM goes idle
>+        https://bugs.webkit.org/show_bug.cgi?id=186064
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        shrinkFootprint was implemented as:
>+        ```
>+        sanitizeStackForVM(this);
>+        deleteAllCode(DeleteAllCodeIfNotCollecting);
>+        heap.collectNow(Synchronousness::Sync);
>+        WTF::releaseFastMallocFreeMemory();
>+        ```
>+        
>+        However, for correctness reasons, deleteAllCode is implemented to do
>+        work when the VM goes idle (no JS is running on the stack). This means
>+        that if shrinkFootprint is called when JS is running on the stack, it
>+        ends up freeing less memory than it could have if it waited to run until
>+        the VM goes idle.
>+        
>+        This patch makes that change. I'm seeing a 10% footprint progression
>+        when testing this against a client of the JSC API.
>+
>+        * API/JSVirtualMachinePrivate.h:
>+        * runtime/VM.cpp:
>+        (JSC::VM::shrinkFootprint):
>+
> 2018-05-29  Caio Lima  <ticaiolima@gmail.com>
> 
>         [ESNext][BigInt] Implement support for "<" and ">" relational operation
>Index: Source/JavaScriptCore/API/JSVirtualMachinePrivate.h
>===================================================================
>--- Source/JavaScriptCore/API/JSVirtualMachinePrivate.h	(revision 232275)
>+++ Source/JavaScriptCore/API/JSVirtualMachinePrivate.h	(working copy)
>@@ -34,8 +34,12 @@
> /*!
> @method
> @discussion Shrinks the memory footprint of the VM by deleting various internal caches,
>- running synchronous garbage collection, and releasing memory back to the OS. For this
>- to free as much memory as possible, do not call this when JavaScript is running on the stack.
>+ running synchronous garbage collection, and releasing memory back to the OS. Note: this
>+ API waits until no JavaScript is running on the stack before it frees any memory. It's
>+ best to call this API when no JavaScript is running on the stack for this reason. However, if
>+ you do call this API when JavaScript is running on the stack, the API will wait until all JavaScript
>+ on the stack finishes running to free memory back to the OS. Therefore, calling this
>+ API may not synchronously free memory.
> */
> 
> - (void)shrinkFootprint; // FIXME: Annotate this with NS_AVAILABLE: <rdar://problem/40071332>.
>Index: Source/JavaScriptCore/runtime/VM.cpp
>===================================================================
>--- Source/JavaScriptCore/runtime/VM.cpp	(revision 232275)
>+++ Source/JavaScriptCore/runtime/VM.cpp	(working copy)
>@@ -779,12 +779,14 @@ void VM::deleteAllCode(DeleteAllCodeEffo
> 
> void VM::shrinkFootprint()
> {
>-    sanitizeStackForVM(this);
>-    deleteAllCode(DeleteAllCodeIfNotCollecting);
>-    heap.collectNow(Synchronousness::Sync);
>-    WTF::releaseFastMallocFreeMemory();
>-    // FIXME: Consider stopping various automatic threads here.
>-    // https://bugs.webkit.org/show_bug.cgi?id=185447
>+    whenIdle([=] () {
>+        sanitizeStackForVM(this);
>+        deleteAllCode(DeleteAllCodeIfNotCollecting);
>+        heap.collectNow(Synchronousness::Sync);
>+        WTF::releaseFastMallocFreeMemory();
>+        // FIXME: Consider stopping various automatic threads here.
>+        // https://bugs.webkit.org/show_bug.cgi?id=185447
>+    });
> }
> 
> SourceProviderCache* VM::addSourceProviderCache(SourceProvider* sourceProvider)

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