I don't know why I didn't get the reply in email, but this is representative of
the real world code.
- Jay
From: Jay K <jayk...@hotmail.com>
Sent: Wednesday, January 12, 2022 6:27 AM
To: cyg...@sourceware.org <cyg...@sourceware.org>
Subject: Re: proc_waiter: error on read of child wait pipe 0x0, Win32 error 6
Ok, here is a small demonstration of the problem.
#include <stdlib.h>
#include <stdio.h>
#include <windows.h>
unsigned __stdcall thread(void* p)
{
unsigned i;
for (i = 0; i < 100; ++i)
system("./a.exe");
return 0;
}
int main()
{
unsigned i;
HANDLE threads[100] = {0};
FILE* f = fopen("a.c", "w");
fprintf(f, "int main() { return 0; }\n");
fclose(f);
system("g++ a.c");
for (i = 0; i < 100; ++i)
threads[i] = CreateThread(0, 0, thread, 0,0,0);
for (i = 0; i < 100; ++i)
WaitForSingleObject(threads[i], -1);
}
$ ./1.exe
0 [main] sh 9287 C:\cygwin64\bin\sh.exe: *** fatal error - internal error
reading the windows environment - too many environment variables?
3001 [main] sh 9287
cygwin_exception::open_stackdumpfile: Dumping stack trace to sh.exe.stackdump
0 [main] sh 9286
C:\cygwin64\bin\sh.exe: *** fatal error - internal error reading the windows
environment - too many environment variables?
Stack trace:
Frame Function Args
000FFFFCD30 00180061C6E (001802795F0, 00180269E81, 00000000000, 000FFFFBB20)
000FFFFCD30 0018004849A (00000000228, 00800000160, 00000000000, 000FFFFCD30)
000FFFFCD30 001800484D2 (00000000000, 00000000000, 00000000000, 00000000000)
000FFFFCD30 0018005F12D (00180158C19, 00000000000, 00000000000, 000FFFFCD30)
000FFFFCD30 00180103AE4 (00000000000, 00000000000, 00000000000, 00000000000)
000FFFFCD30 00180048BC2 (00000000000, 00000000000, 00000000000, 00000000000)
000FFFFFFF0 00180047746 (00000000000, 00000000000, 00000000000, 00000000000)
000FFFFFFF0 001800477F4 (00000000000, 00000000000, 00000000000, 00000000000)
End of stack trace
0 [waitproc] 1 9269 proc_waiter: error on read of child
wait pipe 0x0, Win32 error 6
1078 [waitproc] 1 9269 proc_waiter: error on read of child wait
pipe 0x0, Win32 error 6
4452 [waitproc] 1 9269 proc_waiter: error on read of child wait pipe 0x0,
Win32 error 6
sh: ./a.exe: Bad address
11522 [waitproc] 1 9269 proc_waiter: error on read of child wait pipe 0x0,
Win32 error 6
sh: ./a.exe: Bad address
sh: ./a.exe: Bad address
38623 [waitproc] 1 9269 proc_waiter: error on read of child wait pipe 0x0,
Win32 error 6
48009 [waitproc] 1 9269 proc_waiter: error on read of child wait
pipe 0x0, Win32 error 6
48660 [waitproc] 1 9269 proc_waiter: error on read of child wait pipe 0x0,
Win32 error 6
49909 [waitproc] 1 9269 proc_waiter: error on read of child wait pipe 0x0,
Win32 error 6
I understand I can workaround this, in that the use of threads is silly.
Is this invalid, to mix Win32 threads with cygwin system()?
- Jay
From: Jay K <jayk...@hotmail.com>
Sent: Wednesday, January 12, 2022 5:57 AM
To: cyg...@sourceware.org <cyg...@sourceware.org>
Subject: Re: proc_waiter: error on read of child wait pipe 0x0, Win32 error 6
Um, I know this isn't (yet) diligent/scientific, but must system create this
thread?
#0 0x00007ff811e09e47 in KERNEL32!CreateThread () from
/cygdrive/c/WINDOWS/System32/KERNEL32.DLL
#1 0x00000001800468eb in cygthread::create() () from /usr/bin/cygwin1.dll
#2 0x000000018010645f in pinfo::wait() () from /usr/bin/cygwin1.dll
#3 0x000000018012e562 in proc_subproc(unsigned int, unsigned long) () from
/usr/bin/cygwin1.dll
#4 0x0000000180134e85 in child_info_spawn::worker(char const*, char const*
const*, char const* const*, int, int, int) () from /usr/bin/cygwin1.dll
#5 0x0000000180136729 in spawnve () from /usr/bin/cygwin1.dll
#6 0x0000000180136d05 in spawnvp () from /usr/bin/cygwin1.dll
#7 0x0000000180144683 in system () from /usr/bin/cygwin1.dll
#8 0x000000018018effb in _sigfe () from /usr/bin/cygwin1.dll
#9 0x000000010052884b in QMachine__ExecCommand (t_L_563=0x448ef0
"\260\324\005",
'cause i.e. it complicates any lifetime/management.
I do understand some of the problems here, like needing separate threads to
read stdout/stderr, if they are not equal.
- Jay
From: Jay K
Sent: Wednesday, January 12, 2022 4:12 AM
To: cyg...@sourceware.org <cyg...@sourceware.org>
Subject: proc_waiter: error on read of child wait pipe 0x0, Win32 error 6
I get this a lot:
0 [waitproc] cm3 7641 proc_waiter: error on read of child wait pipe 0x0,
Win32 error 6
452 [waitproc] cm3 7641 proc_waiter: error on read of child wait pipe 0x0,
Win32 error 6
716 [waitproc] cm3 7641 proc_waiter: error on read of child wait pipe 0x0,
Win32 error 6
1652 [waitproc] cm3 7641 proc_waiter: error on read of child wait pipe 0x0,
Win32 error 6
0 [main] sh 7775 C:\cygwin64\bin\sh.exe: *** fatal error - internal error
reading the windows environment - too many environment variables?
Scenario is multi-threaded "launching" a bunch of invocations of gcc.
"launching" was usually spawnve or fork/execve but I changed the code to use
system and it still happens.
I might try to make a small reproducing, if this is not known.
It seems a bit difficult to believe I could cause this internal looking error.
Thank you,
- Jay
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