On 2022-04-16 12:39, Takashi Yano wrote:
I am not sure yet what is essential, but the current code closes
pseudo console only if there is no other process which is attaching
to the pseudo console. I wonder why javac.exe is remaining as
zombie. The parent bash.exe calls ColosePseudoConsole() when
child non-cygwin app is terminated, i.e., after WaitForSingleObject()
for child process handle returns.
https://www.cygwin.com/git/?p=newlib-cygwin.git;a=blob;f=winsup/cygwin/spawn.cc;h=81dba5a941e919ea2514013069aef22c6fad8004;hb=7ac0767053e278f0ce9811bf6f77278bd2f49c20#l1009
What does the "zombie" mean? Is it listed in the process list of
ProcessHacker? I still suspect that the zombie javac.exe holds
the hWritePipe handle leaked from parent bash.exe.
By "zombie" I meant the same thing as in the Linux kernel: a data
structure that remains after a process terminated, but hasn't been
waited for yet (I don't know how this is implemented in Cygwin). So
there is no javac.exe process in ProcessHacker, but "ps" and similar
tools in Cygwin still list "javac".
I'm now trying to create a small reproducer that I can share, and I've
had a first small success this night: I could get a very similar hang
with a simple Makefile and a script with Cygwin 3.3.4. Here is the tree:
make(14479)-+-bash(14484)---bash(14611)
|-bash(14515)---bash(14618)
|-bash(14491)---bash(14500)---bash(14612)
|-bash(14501)---bash(14510)---bash(14605)
|-bash(14505)---bash(14607)
|-bash(14494)---bash(14617)
|-bash(14506)---bash(14513)---bash(14610)
|-bash(14512)---bash(14518)---bash(14615)
|-bash(14486)---bash(14495)---bash(14606)
|-bash(14483)---bash(14490)---bash(14609)
|-bash(14509)---bash(14614)
|-bash(14489)---bash(14608)
|-bash(14499)---bash(14613)
|-bash(14481)---bash(14485)---python(14588)
|-bash(14496)---bash(14504)---bash(14616)
`-bash(14482)---bash(14604)
"python" is a zombie, just as "javac" is in the original case. There is
also a single "conhost.exe" again, and all of its 5 threads are doing
the same things as in the original case (including the signal pipe
thread trying to EnterCriticalSection()). The only difference is that
leaf bash.exe are trying to acquire pcon mutex at a different point [1],
but I guess this difference is not important.
I'll try this reproducer with your patched DLL as well as on another
machine and share it in case of success.
Thanks,
Alexey
[1]
https://www.cygwin.com/git?p=newlib-cygwin.git;a=blob;f=winsup/cygwin/spawn.cc;h=81dba5a941e919ea2514013069aef22c6fad8004;hb=cygwin-3_3_4-release#l697
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