Freeze in Agent 2.0 beta.

[Rein Klazes]

Hi,

When downloading headers form multiple groups Agent often locks up.

The program does the following:

-(Main). main thread creates a sub thread:

| 0009:Call kernel32.CreateThread(00000000,00002000,006648e0,41ac6cb0,00000004,41ac6cb0) ret=006649c9
| 0009: *fd* 23 <- 41
| 0009: new_thread( suspend=1, inherit=0, request_fd=23 )
| 0009: new_thread() = 0 { tid=0021, handle=0xcc }
| 0021: *fd* 27 <- 42
| 0021: *fd* 29 <- 45
| 0021: init_thread( unix_pid=4966, unix_tid=-1, teb=0x40319000, entry=0x404fa110, reply_fd=27, wait_fd=29 )
| 0021: init_thread() = 0 { pid=0008, tid=0021, boot=0, version=126 }
| 0021: select( flags=8, cookie=0x4031ac78, timeout=1068729666.690492 (-0.000050), handles={} )
| 0021: select() = PENDING
| 0009:Ret  kernel32.CreateThread() retval=000000cc ret=006649c9

-(SUB). Sub thread updates some files and finishes with sending a
WM_NULL message to the main thrad:

| 0021:Call user32.PostMessageA(00010026,00000000,00000000,00000000) ret=0058d0d6
| 0021:Call kernel32.GetTickCount() ret=407924ca
| 0021:Ret  kernel32.GetTickCount() retval=000ab0db ret=407924ca
| 0021: send_message( id=0009, type=6, flags=0, win=0x10026, msg=00000000, wparam=00000000, lparam=00000000, x=0, y=0, time=000ab0db, info=00000000, timeout=-1, callback=(nil), data={} )
| 0021: send_message() = 0
| 0021:Ret  user32.PostMessageA() retval=00000001 ret=0058d0d6

-(SUB). Close the thread handle:

| 0021:Call kernel32.CloseHandle(000000cc) ret=006648d0
| 0021: close_handle( handle=0xcc )
| 0021: close_handle() = 0 { fd=-1 }
| 0021:Ret  kernel32.CloseHandle() retval=00000001 ret=006648d0

-(SUB). terminates:

| 0021:Call kernel32.ExitThread(00000000) ret=006648df
| 0021: terminate_thread( handle=0xfffffffe, exit_code=0 )
| 0021: terminate_thread() = 0 { self=1, last=0 }
[snip]
| 0021:Ret  PE DLL (proc=0x4079ad40,module=0x406f0000 L"user32.dll",reason=THREAD_DETACH,res=(nil)) retval=1
| 0021:Call PE DLL (proc=0x40cef0a0,module=0x40cb0000 L"x11drv.dll",reason=THREAD_DETACH,res=(nil))
| 0021:Ret  PE DLL (proc=0x40cef0a0,module=0x40cb0000 L"x11drv.dll",reason=THREAD_DETACH,res=(nil)) retval=1
| 0021:Call PE DLL (proc=0x404c8980,module=0x40480000 L"kernel32.dll",reason=THREAD_DETACH,res=(nil))
| 0021:Ret  PE DLL (proc=0x404c8980,module=0x40480000 L"kernel32.dll",reason=THREAD_DETACH,res=(nil)) retval=1
| 0021: *killed* exit_code=0

-(Main). In the meantime the main thread:
	- gets data from the server (winsok send and rcv)
	- writes to the file
	- processes queued messages until it is empty
	- then is wait on the handle of the subthread:

| 0009:Call kernel32.WaitForSingleObject(000000cc,ffffffff) ret=004ed693

-(Main). which ends immedeately:

| 0009: select( flags=4, cookie=0x406cf4e0, timeout=0, handles={0xcc} )
| 0009: select() = INVALID_HANDLE
| 0009:Ret  kernel32.WaitForSingleObject() retval=ffffffff ret=004ed693

-(Main). close the subthread handle.

| 0009:Call kernel32.CloseHandle(000000cc) ret=004ed69c
| 0009: close_handle( handle=0xcc )
| 0009: close_handle() = INVALID_HANDLE { fd=0 }
| 0009:Ret  kernel32.CloseHandle() retval=00000000 ret=004ed69c

This may repeat a number of times but then without warning:

-(SUB). terminates as usual:

| 0023:Ret  PE DLL (proc=0x4079ad40,module=0x406f0000 L"user32.dll",reason=THREAD_DETACH,res=(nil)) retval=1
| 0023:Call PE DLL (proc=0x40cef0a0,module=0x40cb0000 L"x11drv.dll",reason=THREAD_DETACH,res=(nil))
| 0023:Ret  PE DLL (proc=0x40cef0a0,module=0x40cb0000 L"x11drv.dll",reason=THREAD_DETACH,res=(nil)) retval=1
| 0023:Call PE DLL (proc=0x404c8980,module=0x40480000 L"kernel32.dll",reason=THREAD_DETACH,res=(nil))
| 0023:Ret  PE DLL (proc=0x404c8980,module=0x40480000 L"kernel32.dll",reason=THREAD_DETACH,res=(nil)) retval=1
| 0023: *killed* exit_code=0

-(Main). Finishes its message processing and the waits:

| 0009:Call kernel32.WaitForSingleObject(000000cc,ffffffff) ret=004ed693
| 0009: select( flags=4, cookie=0x406cf4e0, timeout=0, handles={0xcc} )
| 0009: select() = PENDING

And this wait never returns until explicitly killed:

| 0009: *killed* exit_code=0

I looked at many of these sequences. In all of them the subthread
finished well before the main thread executed its Wait. I was looking
for timing differences between the processing of the two threads,
checking whether and when the WM_NULL message gets processed. Nothing
seems to stand out.

Any suggestions how to debug this?

A large cut from the +relay,+server trace is on
http://www.xs4all.nl/~rklazes/temp/agserver.log.bz2

Rein.
-- 
Rein Klazes
rklazes at xs4all.nl