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Date:      Thu, 28 Nov 2019 20:13:38 +0100
From:      Willem Jan Withagen <wjw@digiware.nl>
To:        Eugene Grosbein <eugen@grosbein.net>, FreeBSD Hackers <freebsd-hackers@freebsd.org>
Subject:   Re: Process in T state does not want to die.....
Message-ID:  <cfc428ea-a63c-c827-a29f-4ad8b8e0b963@digiware.nl>
In-Reply-To: <0d698f4e-decf-8d4b-7a05-d5985558fb07@grosbein.net>
References:  <966f830c-bf09-3683-90da-e70aa343cc16@digiware.nl> <3c57e51d-fa36-39a3-9691-49698e8d2124@grosbein.net> <91490c30-45e9-3c38-c55b-12534fd09e28@digiware.nl> <0d698f4e-decf-8d4b-7a05-d5985558fb07@grosbein.net>

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On 28-11-2019 12:04, Eugene Grosbein wrote:
> 28.11.2019 17:37, Willem Jan Withagen wrote:
>
>>> Process in state T is STOPPED and prohibited for execution.
>>> It cannot even process signal like SIGTERM or SIGKILL because they are queied waiting for continuation.
>>> You need to resume it with kill -CONT first.
>> Tried that several times, but does not really have any effect.
>> I could check and see if the signals (TERM, KILL) were waiting somewhere?
>> With procstat??
>>
>> But the original question was more for a way on preventing this state of affairs.
>> Because uptill now the only resolution was to reboot the server, which is not a nice
>> thing for a storage sollution.
>>
>> Hence the: how to debug? question.
> Sometimes background process is (mistakenly) started without closing/redirecting output
> and if it tries to print something, it might get stopped depending on used shell.
Oke, that could very wel be the case....
When starting it prints to console, but I also know it forks. And I have 
seen some dev discusion on
closing so they could be closing before the fork.

> Use ktrace/kdump to verify what's going on with the process if you can reproduce the problem.
> You did not specify which version you use. Sometimes flags shown by ps are wrong due to kernel bugs
> and corrupted process state flag and process is not really Stopped but Exiting for example.
Running 12.1-RELEASE:
FreeBSD cephtest 12.1-RELEASE-p1 FreeBSD 12.1-RELEASE-p1 GENERIC amd64

> ktrace/kdump should show if process got SIGSTOP/SIGTSTP really. And if SIGCONT was delivered.
Thanx for the suggestion, I'll try and read up.
It is a bit of work, but the problem is "easily" reproduced.

--WjW

>
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