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https://issues.apache.org/jira/browse/TS-4207?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15185815#comment-15185815
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ASF GitHub Bot commented on TS-4207:
------------------------------------
GitHub user zwoop opened a pull request:
https://github.com/apache/trafficserver/pull/521
TS-4207 Adds better checks to avoid HostDB crashes in 6.x
As much as I dislike this bandaid fix, it does prevent the crashes that
we've
been experiencing since upgrading to 6.1.x. It's also in line with other
checks for the validity of the rr done in other places. Since the crash is
rather infrequent (once or twice a day on ~30 machines), it's difficult to
track down the exact commit that broke this.
But I did run a build that reverted all HostDB changes since 5.3.x and that
also fixes the crasher. So it's definitely either a fix triggering an old
bug,
or a regression.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/zwoop/trafficserver TS-4207
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/trafficserver/pull/521.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 #521
----
commit 19b233306b89e5e9ad32dc69a957f90f4312b306
Author: Leif Hedstrom <[email protected]>
Date: 2016-03-07T22:34:56Z
TS-4207 Adds better checks to avoid HostDB crashes in 6.x
As much as I dislike this bandaid fix, it does prevent the crashes that
we've
been experiencing since upgrading to 6.1.x. It's also in line with other
checks for the validity of the rr done in other places. Since the crash is
rather infrequent (once or twice a day on ~30 machines), it's difficult to
track down the exact commit that broke this.
But I did run a build that reverted all HostDB changes since 5.3.x and that
also fixes the crasher. So it's definitely either a fix triggering an old
bug,
or a regression.
----
> Crash in HostDB, likely a regression from 5.x
> ---------------------------------------------
>
> Key: TS-4207
> URL: https://issues.apache.org/jira/browse/TS-4207
> Project: Traffic Server
> Issue Type: Bug
> Components: HostDB
> Reporter: Leif Hedstrom
> Priority: Blocker
> Labels: crash
> Fix For: 6.2.0
>
>
> We're seeing a new crash in HostDB, which did not occur in 5.3.x:
> {code}
> (gdb) bt
> #0 0x00002aaaaac7b2bb in HttpSM::process_hostdb_info(HostDBInfo*) () at
> ../../iocore/hostdb/P_HostDBProcessor.h:295
> #1 0x00002aaaaac88b16 in HttpSM::state_hostdb_lookup(int, void*) () at
> HttpSM.cc:2126
> #2 0x00002aaaaac9713d in HttpSM::main_handler(int, void*) () at
> HttpSM.cc:2561
> #3 0x00002aaaaad7803e in reply_to_cont(Continuation*, HostDBInfo*, bool) ()
> at ../../iocore/eventsystem/I_Continuation.h:153
> #4 0x00002aaaaad7eca5 in HostDBContinuation::dnsEvent(int, HostEnt*) () at
> HostDB.cc:1685
> #5 0x00002aaaaad98faf in DNSEntry::postEvent(int, Event*) () at
> ../../iocore/eventsystem/I_Continuation.h:153
> #6 0x00002aaaaae7e420 in EThread::process_event(Event*, int) () at
> I_Continuation.h:153
> #7 0x00002aaaaae7f2ab in EThread::execute() () at UnixEThread.cc:179
> #8 0x00002aaaaae7de06 in spawn_thread_internal(void*) () at Thread.cc:86
> #9 0x00002aaaad6ac9d1 in start_thread () from /lib64/libpthread.so.0
> #10 0x00002aaaae8b58fd in clone () from /lib64/libc.so.6
> {code}
> I think some inlining here complicates things, what it looks like the "r" is
> NULL, but it somehow still ends up using r->rr ?
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