[Bug 970] Intermittent regression tests freeze, possibly due to thread race condition.

[Wine Bugs]

http://bugs.winehq.com/show_bug.cgi?id=970





------- Additional Comments From z_god(a)wanadoo.nl  2003-22-06 06:55 -------
Bug comments restored from Gmane.org: 
 
[Comments made about CVS just after Tue, 13 Aug 2002 19:44:01 +01:00 (BST) 
updates] 
 
Whilst conducting the regression tests (as part of the rolling CVS regression 
testing) I discovered a problem. With the version set to "win20", the process 
froze at one of the wininet DLL tests. This has happened before (see [1]), but 
it only occurs when emulating one of the 16-bit version of Windows (ie "win20", 
"win30" or "win31") and never for other versions. 
 
Sylvain has reported [2] problems with the wininet regression tests. The 
symptoms are the same, but for me the problem is only intermittent. Once I found 
an example of the problem, I haven't been able to reproduce it - even with 
identical CVS trees. 
 
When the problem occurred, I attached gdb to the process and got the following info: 
 
  [...] 
Loaded symbols for /lib/libresolv.so.2 
0x402e7744 in __libc_close () at __libc_close:-1 
-1      __libc_close: No such file or directory. 
        in __libc_close 
(gdb) bt 
#0  0x402e7744 in __libc_close () at __libc_close:-1 
#1  0x400ec9a4 in __DTOR_END__ () 
               from /home/paulm/WINE-cvs/wine/dlls/libntdll.dll.so 
#2  0x400b3df5 in WaitForMultipleObjectsEx (count=0, handles=0x0,  
               wait_all=0, timeout=100, alertable=0) at  
               ../../scheduler/synchro.c:257 
#3  0x400b3b88 in Sleep (timeout=100) at ../../scheduler/synchro.c:178 
#4  0x40358747 in winapi_test (flags=268435456) at tests/http.c:121 
#5  0x40358b36 in func_http () at tests/http.c:184 
#6  0x40358f9d in run_test (name=0xbffffc63 "http.c") at wtmain.c:244 
#7  0x40357037 in __wine_exe_main () at wininet_test.exe.spec.c:133 
#8  0x400aff84 in start_process () at ../../scheduler/process.c:528 
#9  0x400b3f3f in call_on_thread_stack (func=0x400afd2c) 
               at ../../scheduler/sysdeps.c:108 
 
So, to summarise (with some extra bits of information): 
 
The problem occurs when wininet/tests/http.c is testing asynchronous 
HttpSendRequest() (so flags > 0). The problem is triggered at line 121 of  
http.c, i.e.: 
120    while ((flags)&&(!goon)) 
121        Sleep(100); 
 
Sleep(), in turn, just calls WaitForMultipleObjectsEx(). From  
scheduler/synchro.c: 
176     VOID WINAPI Sleep( DWORD timeout ) 
177     { 
178         WaitForMultipleObjectsEx( 0, NULL, FALSE, timeout, FALSE ); 
179     } 
 
 
WaitForMultipleObjectsEx() has problems when it gets to 257: 
256             SERVER_END_REQ; 
257             if (ret == STATUS_PENDING) ret = wait_reply( &cookie ); 
258             if (ret != STATUS_USER_APC) break; 
 
In this case, ret is 1079729528, btw. 
 
AFAIK, __DTOR_END__ (see near bottom of stack) is the destructor for a 
function call in ntdll. I'm probably missing something obvious, but I 
don't see the connection between scheduler/synchro.c:257 and ntdll. The 
closest is wait_reply() (in scheduler/client.c) calls wait_reply_data (in 
same file), which calls NtCurrentTeb(), which is commented as an NTDLL 
function. But there doesn't seem to be an implementation of NtCurrentTeb 
in ntdll. 
 
HTH 
 
Paul. 
 
[1] http://www.winehq.com/hypermail/wine-devel/2002/08/0006.html 
[2] http://www.winehq.com/hypermail/wine-devel/2002/07/0386.html 

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