[jira] [Work logged] (TS-4717) Http2 stack explosion

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/TS-4717?focusedWorklogId=31574&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-31574 ]

ASF GitHub Bot logged work on TS-4717:
--------------------------------------

                Author: ASF GitHub Bot
            Created on: 04/Nov/16 02:21
            Start Date: 04/Nov/16 02:21
    Worklog Time Spent: 10m 
      Work Description: GitHub user sekimura opened a pull request:

    https://github.com/apache/trafficserver/pull/1188

    TS-4717: Http2 stack explosion.

    This is a backport PR of https://github.com/apache/trafficserver/pull/842

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/sekimura/trafficserver ts-4717

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/trafficserver/pull/1188.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #1188
    
----
commit 1e6cc95b0b7c3f1c72750289ee37097afc4d782e
Author: Susan Hinrichs <sh...@ieee.org>
Date:   2016-08-08T18:36:41Z

    TS-4717: Http2 stack explosion.

----


Issue Time Tracking
-------------------

    Worklog Id:     (was: 31574)
    Time Spent: 3.5h  (was: 3h 20m)

> Http2 stack explosion
> ---------------------
>
>                 Key: TS-4717
>                 URL: https://issues.apache.org/jira/browse/TS-4717
>             Project: Traffic Server
>          Issue Type: Bug
>          Components: HTTP/2
>            Reporter: Susan Hinrichs
>            Assignee: Susan Hinrichs
>             Fix For: 7.0.0
>
>          Time Spent: 3.5h
>  Remaining Estimate: 0h
>
> We see this periodically with high traffic loads.  ATS crashes with 7000+ frames on the stack.  The bulk of the frames are the following frame sequence.  
> {code}
> #117 0x00000000005159c8 in Continuation::handleEvent (this=0x2b0bdd101b90, event=100, data=0x2b0bad0c7cf0)
>     at ../iocore/eventsystem/I_Continuation.h:150
> #118 0x000000000064c05d in Http2ClientSession::state_start_frame_read (this=0x2b0bdd101b90, event=100, edata=0x2b0bad0c7cf0)
>     at Http2ClientSession.cc:451
> #119 0x000000000064b0af in Http2ClientSession::main_event_handler (this=0x2b0bdd101b90, event=100, edata=0x2b0bad0c7cf0) at Http2ClientSession.cc:292
> #120 0x00000000005159c8 in Continuation::handleEvent (this=0x2b0bdd101b90, event=100, data=0x2b0bad0c7cf0)
>     at ../iocore/eventsystem/I_Continuation.h:150
> #121 0x000000000064c386 in Http2ClientSession::state_complete_frame_read (this=0x2b0bdd101b90, event=100, edata=0x2b0bad0c7cf0)
>     at Http2ClientSession.cc:483
> #122 0x000000000064b0af in Http2ClientSession::main_event_handler (this=0x2b0bdd101b90, event=100, edata=0x2b0bad0c7cf0) at Http2ClientSession.cc:292
> #123 0x00000000005159c8 in Continuation::handleEvent (this=0x2b0bdd101b90, event=100, data=0x2b0bad0c7cf0)
>     at ../iocore/eventsystem/I_Continuation.h:150
> #124 0x000000000064c05d in Http2ClientSession::state_start_frame_read (this=0x2b0bdd101b90, event=100, edata=0x2b0bad0c7cf0)
>     at Http2ClientSession.cc:451
> {code}
> We had cherry picked in the fix for TS-4209 to correctly enforce the concurrent stream limit.  But in the latest crash of this type, it looks like we are pulling small items from cache, so the stream lives and dies on the stack.  The concurrent active connection count never reaches the limit.
> I am going to try to change the state_state_start_frame_read/state_complete_frame_read logic from recursing handlers to a loop.



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