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Date: Sat, 09 Apr 2022 14:00:59 +0300
From: Alexey Izbyshev <izbyshev@ispras.ru>
To: Takashi Yano <takashi.yano@nifty.ne.jp>
Cc: cygwin@cygwin.com
Subject: Re: Deadlock of the process tree when running make
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On 2022-04-09 13:17, Takashi Yano wrote:

> Attaching gdb to the hanging process and dumping stack by 'bt'
> command for each thread may diagnose more detail.

I decided to simply look at assembly at the point shown in ProcessHacker 
stack trace (cygwin1.dll!feinitialise+0x5ecab) to avoid disturbing the 
process by gdb. And it's clear that the hang is in 
fhandler_pty_slave::reset_switch_to_pcon() at [1]. I've checked that 
there were some changes in that function since 3.3.4. Could they fix 
this deadlock?

[1] 
https://cygwin.com/git/?p=newlib-cygwin.git;a=blob;f=winsup/cygwin/fhandler_tty.cc;h=7bef6958c106c5e78cc90e014081022fd3a205bc;hb=cygwin-3_3_4-release

Thanks,
Alexey