[jira] [Commented] (MESOS-7122) Process reaper should have a dedicated thread to avoid deadlock.

["Yan Xu (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MESOS-7122?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15866436#comment-15866436 ] 

Yan Xu commented on MESOS-7122:
-------------------------------

+1. 

A less severe but pretty annoying thing with reaper is that when writing tests often people forget that you have to unpause the clock for the reaper to work. This is not intuitive.

> Process reaper should have a dedicated thread to avoid deadlock.
> ----------------------------------------------------------------
>
>                 Key: MESOS-7122
>                 URL: https://issues.apache.org/jira/browse/MESOS-7122
>             Project: Mesos
>          Issue Type: Bug
>          Components: libprocess
>            Reporter: James Peach
>
> In a test environment, we saw that libprocess can deadlock when the process reaper is unable to run. 
> This happens in the Mesos HDFS client, which synchronously runs a {{hadoop}} subprocess. If this happens too many times, the {{ReaperProcess}} is never scheduled to reap the subprocess statuses. Since the HDFS {{Future}} never completes, we deadlock with all the threads in the call stack below. If there was a dedicated thread for the {{ReaperProcess}} to run on, or some other way to endure that is is scheduled we could avoid the deadlock.
> {noformat}
> #0  0x00007f67b6ffc68c in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
> #1  0x00007f67b6da12fc in std::condition_variable::wait(std::unique_lock<std::mutex>&) () from /usr/lib64/libstdc++.so.6
> #2  0x00007f67b8b864f6 in process::ProcessManager::wait(process::UPID const&) () from /usr/lib64/libmesos-1.2.0.so
> #3  0x00007f67b8b8d347 in process::wait(process::UPID const&, Duration const&) () from /usr/lib64/libmesos-1.2.0.so
> #4  0x00007f67b8b51a85 in process::Latch::await(Duration const&) () from /usr/lib64/libmesos-1.2.0.so
> #5  0x00007f67b834fc9f in process::Future<Bytes>::await(Duration const&) const () from /usr/lib64/libmesos-1.2.0.so
> #6  0x00007f67b833d700 in mesos::internal::slave::fetchSize(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, Option<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > const&) () from /usr/lib64/libmesos-1.2.0.so
> #7  0x00007f67b833df5e in std::result_of<mesos::internal::slave::FetcherProcess::fetch(mesos::ContainerID const&, mesos::CommandInfo const&, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, Option<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > const&, mesos::SlaveID const&, mesos::internal::slave::Flags const&)::{lambda()#2} ()()>::type process::AsyncExecutorProcess::execute<mesos::internal::slave::FetcherProcess::fetch(mesos::ContainerID const&, mesos::CommandInfo const&, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, Option<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > const&, mesos::SlaveID const&, mesos::internal::slave::Flags const&)::{lambda()#2}>(std::result_of const&, boost::disable_if<std::result_of const&::is_void<std::result_of<mesos::internal::slave::FetcherProcess::fetch(mesos::ContainerID const&, mesos::CommandInfo const&, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, Option<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > const&, mesos::SlaveID const&, mesos::internal::slave::Flags const&)::{lambda()#2} ()()> >, void>::type*) () from /usr/lib64/libmesos-1.2.0.so
> #8  0x00007f67b833a3d5 in std::_Function_handler<void ()(process::ProcessBase*), process::Future<Try<Bytes, Error> > process::dispatch<Try<Bytes, Error>, process::AsyncExecutorProcess, mesos::internal::slave::FetcherProcess::fetch(mesos::ContainerID const&, mesos::CommandInfo const&, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, Option<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > const&, mesos::SlaveID const&, mesos::internal::slave::Flags const&)::{lambda()#2} const&, void*, {lambda()#2}, mesos::internal::slave::FetcherProcess::fetch(mesos::ContainerID const&, mesos::CommandInfo const&, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, Option<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > const&, mesos::SlaveID const&, mesos::internal::slave::Flags const&)::{lambda()#2} const&>(process::PID<process::AsyncExecutorProcess> const&, process::Future (process::PID::*)(mesos::internal::slave::FetcherProcess::fetch(mesos::ContainerID const&, mesos::CommandInfo const&, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, Option<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > const&, mesos::SlaveID const&, mesos::internal::slave::Flags const&)::{lambda()#2} const&, void*), {lambda()#2}, mesos::internal::slave::FetcherProcess::fetch(mesos::ContainerID const&, mesos::CommandInfo const&, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, Option<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > const&, mesos::SlaveID const&, mesos::internal::slave::Flags const&)::{lambda()#2} const&)::{lambda(process::ProcessBase*)#1}>::_M_invoke(std::_Any_data const&, process::ProcessBase*) () from /usr/lib64/libmesos-1.2.0.so
> #9  0x00007f67b8b85ede in process::ProcessManager::resume(process::ProcessBase*) () from /usr/lib64/libmesos-1.2.0.so
> #10 0x00007f67b8b8fc8f in std::thread::_Impl<std::_Bind_simple<process::ProcessManager::init_threads()::{unnamed type#1} ()()> >::_M_run() () from /usr/lib64/libmesos-1.2.0.so
> #11 0x00007f67b6da1470 in ?? () from /usr/lib64/libstdc++.so.6
> #12 0x00007f67b6ff8aa1 in start_thread () from /lib64/libpthread.so.0
> #13 0x00007f67b6a3faad in clone () from /lib64/libc.so.6
> {noformat}



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