[jira] [Updated] (TS-3970) Core in PluginVC

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

     [ https://issues.apache.org/jira/browse/TS-3970?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Leif Hedstrom updated TS-3970:
------------------------------
    Fix Version/s:     (was: 6.1.0)

> Core in PluginVC
> ----------------
>
>                 Key: TS-3970
>                 URL: https://issues.apache.org/jira/browse/TS-3970
>             Project: Traffic Server
>          Issue Type: Bug
>            Reporter: Susan Hinrichs
>            Assignee: Susan Hinrichs
>              Labels: crash
>         Attachments: ts-3970.diff
>
>
> One of our plugins moving from 5.0.1 to 5.3.x (plus 6.0 backports) started seeing the following stack trace with high frequency.
> {code}
> Program terminated with signal 11, Segmentation fault.
> #0 0x000000000054c232 in PluginVC::process_read_side (this=0x2b9ace2f3850, other_side_call=true) at PluginVC.cc:638
> in PluginVC.cc
> #0 0x000000000054c232 in PluginVC::process_read_side (this=0x2b9ace2f3850, other_side_call=true) at PluginVC.cc:638
> #1 0x000000000054be2a in PluginVC::process_write_side (this=0x2b9ace2f3a40, other_side_call=false) at PluginVC.cc:555
> #2 0x000000000054acdb in PluginVC::main_handler (this=0x2b9ace2f3a40, event=1, data=0x2b9b1e32e930) at PluginVC.cc:208
> #3 0x0000000000510c84 in Continuation::handleEvent (this=0x2b9ace2f3a40, event=1, data=0x2b9b1e32e930) at ../iocore/eventsystem/I_Continuation.h:145
> #4 0x000000000079a2a6 in EThread::process_event (this=0x2b9ab63d9010, e=0x2b9b1e32e930, calling_code=1) at UnixEThread.cc:128
> #5 0x000000000079a474 in EThread::execute (this=0x2b9ab63d9010) at UnixEThread.cc:179
> #6 0x0000000000799851 in spawn_thread_internal (a=0x2fea360) at Thread.cc:85
> #7 0x00002b9ab457e9d1 in start_thread () from /lib64/libpthread.so.0
> #8 0x00000030d38e88fd in clone () from /lib64/libc.so.6
> {code}
> The output buffer fetched by PluginVC::process_read_side was NULL.
> I think they reason this appears in 5.3 is due to the fix for TS-3522.  Before that change only one do_io_read was made very early to set up the read from server.  This bug fix delays the real read to later and pulls mbuf out of server_buffer_reader. In some cases for this plugin, the mbuf is NULL by the time we get there.
> I fixed the core by using server_session->read_buffer in the do_io_read instead of server_buffer_reader->mbuf.  This seems to fix the problem.



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