From: Paolo Bonzini <pbonzini@redhat.com>
To: Stefan Hajnoczi <stefanha@redhat.com>, Cornelia Huck <cohuck@redhat.com>
Cc: Stefan Hajnoczi <stefanha@gmail.com>,
Kevin Wolf <kwolf@redhat.com>, Max Reitz <mreitz@redhat.com>,
qemu-devel@nongnu.org, qemu-block@nongnu.org
Subject: Re: [Qemu-devel] qemu-nbd vs 'simple' trace backend vs iotest 147
Date: Fri, 13 Jul 2018 08:40:19 +0200 [thread overview]
Message-ID: <eb3dd1ec-a420-1ede-d42a-4a01c8e9892f@redhat.com> (raw)
In-Reply-To: <20180712163014.GB23738@stefanha-x1.localdomain>
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On 12/07/2018 18:30, Stefan Hajnoczi wrote:
> On Wed, Jul 11, 2018 at 03:33:21PM +0200, Cornelia Huck wrote:
>> The other qemu-nbds (the inet and the unix socket ones from the first
>> run, the second inet one from the second run) have a single thread with
>> the same backtrace I posted above.
>
> We just discussed this on IRC, but for the record:
>
> qemu-nbd --fork will fork the process after the simpletrace write-out
> thread has been spawned. The child process lacks this thread (due to
> how fork(2) handles multithreading). Either qemu-nbd needs to
> initialize tracing later (but that means we cannot trace early init) or
> simpletrace needs a way to respawn the write-out thread.
You can use pthread_atfork for this.
Paolo
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next prev parent reply other threads:[~2018-07-13 6:40 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-09 13:45 [Qemu-devel] qemu-nbd vs 'simple' trace backend vs iotest 147 Cornelia Huck
2018-07-11 13:06 ` Stefan Hajnoczi
2018-07-11 13:15 ` Cornelia Huck
2018-07-11 13:33 ` Cornelia Huck
2018-07-12 16:30 ` Stefan Hajnoczi
2018-07-13 6:40 ` Paolo Bonzini [this message]
2018-07-13 13:53 ` Stefan Hajnoczi
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