[jira] [Reopened] (TS-2137) Use eventfd instread of pthread signal/wait in ATS

["Leif Hedstrom (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/TS-2137?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Leif Hedstrom reopened TS-2137:
-------------------------------


Reopening: It looks like this commit can trigger the assert on the write(). User fbanna on IRC reports:
{code}
TrafficServer] using root directory '/usr'
FATAL: EventNotify.cc:73: failed assert `nr == sizeof(uint64_t)`
/usr/bin/traffic_server - STACK TRACE:
3:14
i keep getting those in traffic.out
{code}

                
> Use eventfd instread of pthread signal/wait in ATS
> --------------------------------------------------
>
>                 Key: TS-2137
>                 URL: https://issues.apache.org/jira/browse/TS-2137
>             Project: Traffic Server
>          Issue Type: Improvement
>          Components: Core, Logging, Stats
>            Reporter: Yunkai Zhang
>            Assignee: Yunkai Zhang
>             Fix For: 4.1.0
>
>         Attachments: 0001-TS-2137-Forgot-to-add-header-guide-in-EventNotify.h.patch, 0001-TS-2137-Use-eventfd-instread-of-pthread-signal-wait-.patch, 0001-TS-2137-Use-eventfd-instread-of-pthread-signal-wait-.V2.patch, 0001-TS-2137-Use-eventfd-instread-of-pthread-signal-wait-.V3.patch, 0001-TS-2137-Use-eventfd-instread-of-pthread-signal-wait-.V4.patch, eventfd_vs_pthread_cond_benchmark.tar.gz
>
>
> pthread_cond_signal/wait is used in several places in ATS, including but not limited:
> 1) Logging system.
> 2) ProtectedQueue in event system.
> 3) RecProcess in stats system.
> As we known, pthread_cond_signal() need to take lock, it'll cause more context switch than eventfd.
> I have wrote a simple benchmark program to compare the speed of eventfd and pthread_cond notify mechanism.
> You can get the benchmark program from attachment: https://issues.apache.org/jira/secure/attachment/12598570/eventfd_vs_pthread_cond_benchmark.tar.gz, and test it by yourself if interesting.
> What the program do is that:
> 1) Create 10 producer threads and 1 consumer thread.
> 2) Producer threads will notify consumer concurrently in a loop.
> 3) The consumer thread will receive notification up to a given loop times.
> Here is my testing result, the command line argument is loop times(1000000) of consumer:
> {code}
> [eventfd_vs_pthread_cond_benchmark]$ ls
> main.cc  Makefile
> [eventfd_vs_pthread_cond_benchmark]$ make
> g++ -g -o eventfd_test main.cc -DHAVE_EVENTFD -lpthread
> g++ -g -o pthread_cond_test main.cc -lpthread
> [eventfd_vs_pthread_cond_benchmark]$ ls
> eventfd_test  main.cc  Makefile  pthread_cond_test
> [eventfd_vs_pthread_cond_benchmark]$ time ./eventfd_test 1000000
> real    0m11.644s
> user    0m1.517s
> sys     1m31.179s
> [eventfd_vs_pthread_cond_benchmark]$ time ./pthread_cond_test 1000000
> real    0m57.438s
> user    0m30.152s
> sys     6m7.289s
> {code}
> We can see that eventfd is about 5 times faster than pthread_cond notify mechanism.

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