Commit 82158184 authored by Tooru Fujisawa's avatar Tooru Fujisawa
Browse files

Bug 1738282 - Delete ScriptPreloader singleton after CCPostLastCycleCollection phase. r=mccr8 

This stops destructing the stencils held by ScriptPreloader on release build,
to avoid the shutdown hang caused by thrashing.

Also:
  * Move ScriptPreloader::Cleanup from xpcom-shutdown notification to ScriptPreloader destructor, given there's no reason for having 2 steps
  * Replace ClearOnShutdown call with explicit function call for the singleton deletion, for simplicity
  * Remove now-unused PostJSShutDown phase

Differential Revision: https://phabricator.services.mozilla.com/D130839
parent b34f26e7

js/xpconnect/loader/ScriptPreloader.cpp

+34 −29
Original line number Diff line number Diff line
@@ -14,7 +14,6 @@ 
#include "mozilla/URLPreloader.h"



#include "mozilla/ArrayUtils.h"

#include "mozilla/ClearOnShutdown.h"

#include "mozilla/Components.h"

#include "mozilla/FileUtils.h"

#include "mozilla/IOBuffers.h"
@@ -47,7 +46,6 @@ 
#define DOC_ELEM_INSERTED_TOPIC "document-element-inserted"

#define CONTENT_DOCUMENT_LOADED_TOPIC "content-document-loaded"

#define CACHE_WRITE_TOPIC "browser-idle-startup-tasks-finished"

#define CLEANUP_TOPIC "xpcom-shutdown"

#define CACHE_INVALIDATE_TOPIC "startupcache-invalidate"



// The maximum time we'll wait for a child process to finish starting up before
@@ -105,25 +103,24 @@ nsresult ScriptPreloader::CollectReports(nsIHandleReportCallback* aHandleReport, 
  return NS_OK;

}



ScriptPreloader& ScriptPreloader::GetSingleton() {

  static UniquePtr<AutoMemMap> cacheDataSingleton;

  static RefPtr<ScriptPreloader> singleton;

StaticRefPtr<ScriptPreloader> ScriptPreloader::gScriptPreloader;

StaticRefPtr<ScriptPreloader> ScriptPreloader::gChildScriptPreloader;

UniquePtr<AutoMemMap> ScriptPreloader::gCacheData;

UniquePtr<AutoMemMap> ScriptPreloader::gChildCacheData;



  if (!singleton) {

ScriptPreloader& ScriptPreloader::GetSingleton() {

  if (!gScriptPreloader) {

    if (XRE_IsParentProcess()) {

      cacheDataSingleton = MakeUnique<AutoMemMap>();

      singleton = new ScriptPreloader(cacheDataSingleton.get());

      singleton->mChildCache = &GetChildSingleton();

      Unused << singleton->InitCache();

      ClearOnShutdown(&cacheDataSingleton, ShutdownPhase::JSPostShutDown);

      gCacheData = MakeUnique<AutoMemMap>();

      gScriptPreloader = new ScriptPreloader(gCacheData.get());

      gScriptPreloader->mChildCache = &GetChildSingleton();

      Unused << gScriptPreloader->InitCache();

    } else {

      singleton = &GetChildSingleton();

      gScriptPreloader = &GetChildSingleton();

    }



    ClearOnShutdown(&singleton);

  }



  return *singleton;

  return *gScriptPreloader;

}



// The child singleton is available in all processes, including the parent, and
@@ -150,21 +147,30 @@ ScriptPreloader& ScriptPreloader::GetSingleton() { 
//  probably use the cache data written during this session if there was no

//  previous cache file, but I'd rather do that as a follow-up.

ScriptPreloader& ScriptPreloader::GetChildSingleton() {

  static UniquePtr<AutoMemMap> cacheDataSingleton;

  static RefPtr<ScriptPreloader> singleton;



  if (!singleton) {

    cacheDataSingleton = MakeUnique<AutoMemMap>();

    singleton = new ScriptPreloader(cacheDataSingleton.get());

  if (!gChildScriptPreloader) {

    gChildCacheData = MakeUnique<AutoMemMap>();

    gChildScriptPreloader = new ScriptPreloader(gChildCacheData.get());

    if (XRE_IsParentProcess()) {

      Unused << singleton->InitCache(u"scriptCache-child"_ns);

      Unused << gChildScriptPreloader->InitCache(u"scriptCache-child"_ns);

    }

  }



    ClearOnShutdown(&singleton);

    ClearOnShutdown(&cacheDataSingleton, ShutdownPhase::JSPostShutDown);

  return *gChildScriptPreloader;

}



  return *singleton;

/* static */

void ScriptPreloader::DeleteSingleton() {

  gScriptPreloader = nullptr;

  gChildScriptPreloader = nullptr;

}



/* static */

void ScriptPreloader::DeleteCacheDataSingleton() {

  MOZ_ASSERT(!gScriptPreloader);

  MOZ_ASSERT(!gChildScriptPreloader);



  gCacheData = nullptr;

  gChildCacheData = nullptr;

}



void ScriptPreloader::InitContentChild(ContentParent& parent) {
@@ -229,10 +235,11 @@ ScriptPreloader::ScriptPreloader(AutoMemMap* cacheData) 
    obs->AddObserver(this, CACHE_WRITE_TOPIC, false);

  }



  obs->AddObserver(this, CLEANUP_TOPIC, false);

  obs->AddObserver(this, CACHE_INVALIDATE_TOPIC, false);

}



ScriptPreloader::~ScriptPreloader() { Cleanup(); }



void ScriptPreloader::Cleanup() {

  // Wait for any pending parses to finish before clearing the mScripts

  // hashtable, since the parse tasks depend on memory allocated by those
@@ -333,8 +340,6 @@ nsresult ScriptPreloader::Observe(nsISupports* subject, const char* topic, 
    FinishContentStartup();

  } else if (!strcmp(topic, "timer-callback")) {

    FinishContentStartup();

  } else if (!strcmp(topic, CLEANUP_TOPIC)) {

    Cleanup();

  } else if (!strcmp(topic, CACHE_INVALIDATE_TOPIC)) {

    InvalidateCache();

  }

js/xpconnect/loader/ScriptPreloader.h

+14 −4
Original line number Diff line number Diff line
@@ -84,9 +84,19 @@ class ScriptPreloader : public nsIObserver, 
  NS_DECL_NSINAMED

  NS_DECL_NSIASYNCSHUTDOWNBLOCKER



 private:

  static StaticRefPtr<ScriptPreloader> gScriptPreloader;

  static StaticRefPtr<ScriptPreloader> gChildScriptPreloader;

  static UniquePtr<AutoMemMap> gCacheData;

  static UniquePtr<AutoMemMap> gChildCacheData;



 public:

  static ScriptPreloader& GetSingleton();

  static ScriptPreloader& GetChildSingleton();



  static void DeleteSingleton();

  static void DeleteCacheDataSingleton();



  static ProcessType GetChildProcessType(const nsACString& remoteType);



  // Fill some options that should be consistent across all scripts stored
@@ -137,7 +147,7 @@ class ScriptPreloader : public nsIObserver, 
  static void InitContentChild(dom::ContentParent& parent);



 protected:

  virtual ~ScriptPreloader() = default;

  virtual ~ScriptPreloader();



 private:

  enum class ScriptStatus {
@@ -515,9 +525,9 @@ class ScriptPreloader : public nsIObserver, 
  nsCOMPtr<nsITimer> mSaveTimer;



  // The mmapped cache data from this session's cache file.

  // The instance is held by the static variable in GetSingleton or

  // GetChildSingleton, and its lifetime is guaranteed to be longer than

  // ScriptPreloader instance.

  // The instance is held by either `gCacheData` or `gChildCacheData` static

  // fields, and its lifetime is guaranteed to be longer than ScriptPreloader

  // instance.

  AutoMemMap* mCacheData;



  Monitor mMonitor;

xpcom/base/AppShutdown.cpp

+1 −2
Original line number Diff line number Diff line
@@ -60,8 +60,7 @@ const char* sPhaseObserverKeys[] = { 
    "xpcom-shutdown-threads",           // XPCOMShutdownThreads

    nullptr,                            // XPCOMShutdownLoaders

    nullptr,                            // XPCOMShutdownFinal

    nullptr,                            // CCPostLastCycleCollection

    nullptr                             // PostJSShutDown

    nullptr                             // CCPostLastCycleCollection

};



static_assert(sizeof(sPhaseObserverKeys) / sizeof(sPhaseObserverKeys[0]) ==

xpcom/base/ShutdownPhase.h

+0 −1
Original line number Diff line number Diff line
@@ -24,7 +24,6 @@ enum class ShutdownPhase { 
  XPCOMShutdownLoaders,

  XPCOMShutdownFinal,

  CCPostLastCycleCollection,

  JSPostShutDown,

  ShutdownPhase_Length,         // never pass this value

  First = AppShutdownConfirmed  // for iteration

};

xpcom/build/XPCOMInit.cpp

+2 −1
Original line number Diff line number Diff line
@@ -715,6 +715,7 @@ nsresult ShutdownXPCOM(nsIServiceManager* aServMgr) { 
      mozilla::ShutdownPhase::CCPostLastCycleCollection);



  mozilla::scache::StartupCache::DeleteSingleton();

  mozilla::ScriptPreloader::DeleteSingleton();



  PROFILER_MARKER_UNTYPED("Shutdown xpcom", OTHER);
@@ -733,7 +734,7 @@ nsresult ShutdownXPCOM(nsIServiceManager* aServMgr) { 
    sInitializedJS = false;

  }



  mozilla::KillClearOnShutdown(ShutdownPhase::JSPostShutDown);

  mozilla::ScriptPreloader::DeleteCacheDataSingleton();



  // Release shared memory which might be borrowed by the JS engine.

  xpc::SelfHostedShmem::Shutdown();