[Python-Dev] refleaks & test_tcl & threads

[Tim Peters]

[Thomas Wouters]
> ...
> One remaining issue with refleakhunting on my machine is that test_tcl can't
> stand being run twice. Even without -R, this makes Python hang while waiting
> for a mutex in the second run through test_tcl:
>
> ...trunk $ ./python -E -tt Lib/test/regrtest test_tcl test_tcl
>
> Attaching gdb to the hung process shows this unenlightening trace:
> #0  0x00002b7d6629514b in __lll_mutex_lock_wait () from /lib/libpthread.so.0
> #1  0x00002b7d6639a280 in completed.4801 () from /lib/libpthread.so.0
> #2  0x0000000000000004 in ?? ()
> #3  0x00002b7d66291dca in pthread_mutex_lock () from /lib/libpthread.so.0
> #4  0x0000000000000000 in ?? ()
>
> The process has one other thread, which is stuck here:
> #0  0x00002b7d667f14d6 in __select_nocancel () from /lib/libc.so.6
> #1  0x00002b7d67512d8c in Tcl_WaitForEvent () from /usr/lib/libtcl8.4.so.0
> #2  0x00002b7d66290b1c in start_thread () from /lib/libpthread.so.0
> #3  0x00002b7d667f8962 in clone () from /lib/libc.so.6
> #4  0x0000000000000000 in ?? ()
>
> It smells like test_tcl or Tkinter is doing something wrong with regards to
> threads. I can reproduce this on a few machines, but all of them run newish
> linux kernels with newish glibc's and newish tcl/tk. At least in kernel/libc
> land, various thread related things changed of late. I don't have access to
> other machines with tcl/tk right now, but I wonder if anyone can reproduce
> this in different situations.

FYI, there's no problem running test_tcl with -R on WinXP Pro SP2 from
current trunk:

C:\Code\python\PCbuild>python_d  -E -tt ../lib/test/regrtest.py -R:: test_tcl
test_tcl
beginning 9 repetitions
123456789
.........
1 test OK.
[27306 refs]

That's using Tcl/Tk 8.4.12 (I don't know what newish means in Tcl-land
these days).