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https://issues.apache.org/jira/browse/TS-4970?focusedWorklogId=31117&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-31117
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ASF GitHub Bot logged work on TS-4970:
--------------------------------------
Author: ASF GitHub Bot
Created on: 26/Oct/16 20:00
Start Date: 26/Oct/16 20:00
Worklog Time Spent: 10m
Work Description: Github user jacksontj commented on the issue:
https://github.com/apache/trafficserver/pull/1108
Closing the PR-- as we'll take care of this in Jira.
Issue Time Tracking
-------------------
Worklog Id: (was: 31117)
Time Spent: 5h (was: 4h 50m)
> Crash in INKVConnInternal when handle_event is called after destroy()
> ---------------------------------------------------------------------
>
> Key: TS-4970
> URL: https://issues.apache.org/jira/browse/TS-4970
> Project: Traffic Server
> Issue Type: Bug
> Components: HTTP
> Reporter: Thomas Jackson
> Assignee: Thomas Jackson
> Fix For: 7.1.0
>
> Time Spent: 5h
> Remaining Estimate: 0h
>
> We've noticed a few crashes for requests using SPDY (on ATS 5.2.x and 6..x)
> where the downstream origin is down with a backtrace that looks something
> like:
> {code}
> (gdb) bt
> #0 0x0000000000000000 in ?? ()
> #1 0x00000000004cfe54 in set_continuation (this=0x2afe63a93530, event=1,
> edata=0x2afe6399fc40) at ../iocore/eventsystem/P_VIO.h:104
> #2 INKVConnInternal::handle_event (this=0x2afe63a93530, event=1,
> edata=0x2afe6399fc40) at InkAPI.cc:1060
> #3 0x00000000006f8e65 in handleEvent (this=0x2afe3dd07000, e=0x2afe6399fc40,
> calling_code=1) at I_Continuation.h:146
> #4 EThread::process_event (this=0x2afe3dd07000, e=0x2afe6399fc40,
> calling_code=1) at UnixEThread.cc:144
> #5 0x00000000006f993b in EThread::execute (this=0x2afe3dd07000)
> at UnixEThread.cc:195
> #6 0x00000000006f832a in spawn_thread_internal (a=0x2afe3badf400)
> at Thread.cc:88
> #7 0x0000003861c079d1 in start_thread () from /lib64/libpthread.so.0
> #8 0x00000038614e8b5d in clone () from /lib64/libc.so.6
> {code}
> Which looks a bit odd-- as frame 0 is missing. From digging into it a bit
> more (with the help of [~amc]) we found that the VC we where calling was an
> INKContInternal (meaning an INKVConnInternal):
> {code}
> (gdb) p (INKVConnInternal) *vc_server
> $5 = {<INKContInternal> = {<DummyVConnection> = {<VConnection> =
> {<Continuation> = {<force_VFPT_to_top> = {_vptr.force_VFPT_to_top =
> 0x2afe63a93170},
> handler = (int (Continuation::*)(Continuation *, int,
> void *)) 0x4cfd90 <INKVConnInternal::handle_event(int, void*)>, mutex = {
> m_ptr = 0x0}, link = {<SLink<Continuation>> = {next = 0x0},
> prev = 0x0}}, lerrno = 20600}, <No data fields>},
> mdata = 0xdeaddead, m_event_func = 0x2afe43c18490
> <(anonymous namespace)::handleTransformationPluginEvents(TSCont,
> TSEvent, void*)>, m_event_count = 0, m_closed = -1, m_deletable = 1,
> m_deleted = 1,
> m_free_magic = INKCONT_INTERN_MAGIC_ALIVE}, m_read_vio = {_cont = 0x0,
> nbytes = 0, ndone = 0, op = 0, buffer = {mbuf = 0x0, entry = 0x0},
> vc_server = 0x0, mutex = {m_ptr = 0x0}}, m_write_vio = {_cont = 0x0,
> nbytes = 122, ndone = 0, op = 0, buffer = {mbuf = 0x0, entry = 0x0},
> vc_server = 0x2afe63a93530, mutex = {m_ptr = 0x0}},
> m_output_vc = 0x2afe63091a88}
> {code}
> From looking at the debug logs that lead up to the crash, I'm seeing that
> some events (namely timeout events) are being called after the VConn has been
> destroy()'d . This lead me to find that INKVConnInternal::handle_event is
> actually checking if that is the case-- and then re-destroying everything,
> which makes no sense.
> So although the ideal would be to not call handle_event on a closed VConn,
> crashing is definitely not acceptable. My solution is to continue to only
> call the event handler if the VConn hasn't been deleted-- but instead of
> attempting to re-destroy the connection, we'll leave it be (unless we are in
> debug mode-- where I'll throw in an assert).
> I did some looking at this on ATS7 and it looks like this is all fixed by the
> cleanup of the whole free-ing stuff for VConns
> (https://github.com/apache/trafficserver/pull/752/files).
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