Bug 217363

This test is also crashing in more bots than in gtk-release-wayland bot.

And it also times out sometimes.

This is a summary of what happened on the bots recently:

gtk-release: crashed 171 times on the last 4000 runs
gtk-debug: crashed 1 times and timed out 296 times on the last 4000 runs
wpe-release crashed 97 times and timed out 11 times on the last 4000 runs
wpe-debug: timed out 330 times on the last 4000 runs

(In reply to Carlos Alberto Lopez Perez from comment #1)
> This test is also crashing in more bots than in gtk-release-wayland bot.
> 
> And it also times out sometimes.
> 
> This is a summary of what happened on the bots recently:
> 
> gtk-release: crashed 171 times on the last 4000 runs
> gtk-debug: crashed 1 times and timed out 296 times on the last 4000 runs
> wpe-release crashed 97 times and timed out 11 times on the last 4000 runs
> wpe-debug: timed out 330 times on the last 4000 runs

With "this test" I wanted to mean here the test js/throw-large-string-oom.html 

For the other 2 I no longer see them crashing. 

Updated expectations on r268903

I have reproduced this in the minibrowser as well. I was attaching gdb to the WebProcess in a computer with very limited RAM. This caused enough RAM to be used to trigger the memory pressure handler in the MiniBrowser, and it crashed there.

Here is the backtrace, same as reported before, but resolving the pointers:

ASSERTION FAILED: RunLoop::isMain()
#0  WTFCrash() () at ../../Source/WTF/wtf/Assertions.cpp:295
#1  0x00007f6bdd2309b7 in CRASH_WITH_INFO(...) () at DerivedSources/ForwardingHeaders/wtf/Assertions.h:713
#2  0x00007f6bde1df52c in WebKit::networkProcessesSet() () at ../../Source/WebKit/UIProcess/Network/NetworkProcessProxy.cpp:90
#3  0x00007f6bde1df5ad in WebKit::NetworkProcessProxy::allNetworkProcesses() () at ../../Source/WebKit/UIProcess/Network/NetworkProcessProxy.cpp:98
#4  0x00007f6bdde8063a in WebKit::WebProcessPool::sendMemoryPressureEvent(bool) (this=0x7f6bc44d6000, isCritical=false) at ../../Source/WebKit/UIProcess/WebProcessPool.cpp:443
#5  0x00007f6bde2d4e53 in operator()() const (__closure=0x7f6bc44fa6a8) at ../../Source/WebKit/UIProcess/linux/MemoryPressureMonitor.cpp:383
#6  0x00007f6bde2d60a6 in WTF::Detail::CallableWrapper<WebKit::MemoryPressureMonitor::start()::<lambda()>, void>::call(void) (this=0x7f6bc44fa6a0) at DerivedSources/ForwardingHeaders/wtf/Function.h:52
#7  0x00007f6bdd233fd3 in WTF::Function<void ()>::operator()() const (this=0x7f6b7dbfac30) at DerivedSources/ForwardingHeaders/wtf/Function.h:83
#8  0x00007f6bce715839 in WTF::Thread::entryPoint(WTF::Thread::NewThreadContext*) (newThreadContext=0x7f6bc44eb410) at ../../Source/WTF/wtf/Threading.cpp:179
#9  0x00007f6bce7a6191 in WTF::wtfThreadEntryPoint(void*) (context=0x7f6bc44eb410) at ../../Source/WTF/wtf/posix/ThreadingPOSIX.cpp:213
#10 0x00007f6bc87674d2 in start_thread (arg=<optimized out>) at pthread_create.c:477
#11 0x00007f6bc64852a3 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Note this is the code that starts and runs the MemoryPressureMonitor, very clearly on its own thread.

void MemoryPressureMonitor::start()
{
    if (m_started)
        return;

    m_started = true;

    Thread::create("MemoryPressureMonitor", [] {
        [...]
        while (true) {
            [...]
            if (usedPercentage >= s_memoryPresurePercentageThreshold) {
                [...]
                for (auto* processPool : WebProcessPool::allProcessPools())
                    processPool->sendMemoryPressureEvent([...]);

Then WebProcessPool::sendMemoryPressureEvent() needs to traverse allNetworkProcesses()

void WebProcessPool::sendMemoryPressureEvent([...])
{
    [...]
    for (auto networkProcess : NetworkProcessProxy::allNetworkProcesses())

But networkProcessesSet() assumes it will only ever be used in the main thread, which is not the case here.

static HashSet<NetworkProcessProxy*>& networkProcessesSet()
{
    ASSERT(RunLoop::isMain());
    static NeverDestroyed<HashSet<NetworkProcessProxy*>> set;
    return set;
}

Created attachment 419219 [details]
Patch

Committed r272362: <https://trac.webkit.org/changeset/272362>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 419219 [details].

<rdar://problem/73970229>