Check that all shared workers are terminated.

content/browser/renderer_host/render_process_host_impl.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Represents the browser side of the browser <--> renderer communication
 // channel. There will be one RenderProcessHost per renderer process.
 
 #include "content/browser/renderer_host/render_process_host_impl.h"
 
 #include <algorithm>
@@ skipping 694 matching lines @@
       NOTREACHED() << "There should be only one RenderProcessHost when running "
                    << "in-process.";
   }
 }
 
 void RenderProcessHostImpl::RegisterRendererMainThreadFactory(
     RendererMainThreadFactoryFunction create) {
   g_renderer_main_thread_factory = create;
 }
 
+// static
+// TODO(alokp): Remove after collecting crash data.
+// Temporary checks to verify that all shared workers are terminated.

[horo, 2016/08/09 04:03:24]

Nit: s/shared workers/shared workers and service workers/

|worker_ref_count_| is used for both shared workers and service workers.

So RenderProcessHostImpl::CheckAllWorkersTerminate() is verifying that all
shared workers and service workers are terminated.

[alokp, 2016/08/09 05:07:26]

Thanks for reviewing. I just commented about shared worker because in
BrowserProcessSubThread::IOThreadPreCleanUp, I am only checking shared workers.
Do you suggest a corresponding check for service worker as well?

[horo, 2016/08/09 06:01:26]

I just suggested that you should change the comment of
RenderProcessHostImpl::CheckAllWorkersTerminated().

But...

Could you please explain why you want to check that all shared workers are
terminated for the bug?
This bug 608049 is caused by unclosed AudioOutputStream instance.

I thought that it is because shared workers can open AudioOutputStream.
But AudioContextConstructor is exposed only in window.
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/modules/webaud...
So I think shared workers can't open AudioOutputStream.
And also, service workers can't open AudioOutputStream.

Is my understanding correct?

[alokp, 2016/08/09 06:35:27]

For more context see crbug.com/628192

All audio streams will get closed if RenderProcessHostImpl::Cleanup is called.
In the past I added a few checks here https://codereview.chromium.org/2133813002
and discovered that worker_ref_count_ > 0 is preventing RenderProcessHostImpl(s)
from getting cleaned up. This patch seeks to further understand why
shared/service workers are not getting cleaned up.

I am not familiar with shared/service workers. I would appreciate any help with
diagnosing it further.

[horo, 2016/08/09 09:00:52]

Ah I got it.

I checked ServiceWorkerProcessManager code now.
And I think ServiceWorkerProcessManager::Shutdown() is correctly calling
DecrementWorkerRefCount.

BrowserMainRunnerImpl::Shutdown()
-> BrowserMainLoop::ShutdownThreadsAndCleanUp()
 -> ChromeBrowserMainParts::PostMainMessageLoopRun()
  -> BrowserProcessImpl::StartTearDown()
   -> ProfileManager::~ProfileManager()
    -> ProfileInfo::~ProfileInfo()
     -> ProfileDestroyer::DestroyProfileWhenAppropriate()
      -> Profile::MaybeSendDestroyedNotification()
       -> BrowserContext::NotifyWillBeDestroyed()
        -> BrowserContext::ForEachStoragePartition()
         -> ShutdownServiceWorkerContext()
          -> ServiceWorkerProcessManager::Shutdown()
           -> RenderProcessHostImpl::DecrementWorkerRefCount()

But there may be edge cases that SharedWorkerServiceImpl doesn't correctly call
DecrementWorkerRefCount.

+// It is suspected that shared workers prevent render process hosts
+// from shutting down: crbug.com/608049
+void RenderProcessHostImpl::CheckAllWorkersTerminated() {
+  iterator iter(AllHostsIterator());
+  while (!iter.IsAtEnd()) {
+    RenderProcessHostImpl* host =
+        static_cast<RenderProcessHostImpl*>(iter.GetCurrentValue());
+    CHECK_EQ(0, host->worker_ref_count_);

[falken, 2016/09/02 07:47:45]

This would infinitely loop, no? iter.Advance() should be called.

+  }
+}
+
 RenderProcessHostImpl::~RenderProcessHostImpl() {
 #ifndef NDEBUG
   DCHECK(is_self_deleted_)
       << "RenderProcessHostImpl is destroyed by something other than itself";
 #endif
 
   // Make sure to clean up the in-process renderer before the channel, otherwise
   // it may still run and have its IPCs fail, causing asserts.
   in_process_renderer_.reset();
 
@@ skipping 2103 matching lines @@
   LOG(ERROR) << "Terminating render process for bad Mojo message: " << error;
 
   // The ReceivedBadMessage call below will trigger a DumpWithoutCrashing. Alias
   // enough information here so that we can determine what the bad message was.
   base::debug::Alias(&error);
   bad_message::ReceivedBadMessage(process.get(),
                                   bad_message::RPH_MOJO_PROCESS_ERROR);
 }
 
 }  // namespace content