Debugging the BOINC Windows client

Symbol Files

Symbol files are used by various Windows debugging engines to match up memory addresses to symbol names. Symbol names are names of variables, functions, and subroutines that a developer has named a piece of code before the compilation process.

Symbol files for BOINC can be found on http://boinc.berkeley.edu/dl/

The files generally start out like boinc_xxx_pdb.zip where the xxx is the version of BOINC you are running.

The uncompressed files should be stored in the same directory as BOINC.

Crashes

If either BOINC or the BOINC Manager crash, (they unexpectedly stop running or disappear), there should be some diagnostic information recorded in stderrdae.txt for BOINC and stderrgui.txt for the BOINC Manager.

The diagnostic information we are looking for is called a call stack which is described below.

Call stacks

Call stacks help us identify where the problem is by telling us which file and what line number in the source code the error occurred in.

Here is an example of a good call stack:

***UNHANDLED EXCEPTION****
Reason: Access Violation (0xc0000005) at address 0x00411A87 write attempt to address 0x00000000

1: 06/08/05 15:07:01
1: c:\boincsrc\main\boinc\client\cs_benchmark.c(310) +8 bytes (CLIENT_STATE::cpu_benchmarks_poll)
1: c:\boincsrc\main\boinc\client\client_state.c(431) +0 bytes (CLIENT_STATE::do_something)

Here is an example of a bad call stack:

***UNHANDLED EXCEPTION****
Reason: Access Violation (0xc0000005) at address 0x7C34FEDC read attempt to address 0x05595D90

1: 06/08/05 00:36:54
1: SymGetLineFromAddr(): GetLastError = 126
1: SymGetLineFromAddr(): GetLastError = 126
1: SymGetLineFromAddr(): GetLastError = 126
1: SymGetLineFromAddr(): GetLastError = 126

Extracting call stacks

If we need a call stack to help solve a problem that doesn't manifest itself as a crash you can still extract a call stack from a running program using some freeware tools Microsoft publishes called Debugging Tools for Windows.

The Debugging Tools for Windows can be found on ​Debugging Tools for Windows

Once these tools are installed on your machine and the symbol files are extracted to the BOINC installation directory you can run 'WinDBG.exe' and attach to the 'BOINC.exe' process through the file menu to begin your debugging session. Once 'WinDBG.exe' has attached itself to 'BOINC.exe' you can view the call stack by typing 'kb' in the command window and then hitting enter.

Here is an example of the output 'WinDBG.exe' displays when it dumps a call stack:

ChildEBP RetAddr  Args to Child
0012fafc 7c821364 77e42439 00000000 0012fb40 ntdll!KiFastSystemCallRet
0012fb00 77e42439 00000000 0012fb40 ffffff4a ntdll!NtDelayExecution+0xc
0012fb68 77e424b7 00000064 00000000 0012fee0 kernel32!SleepEx+0x68
*** WARNING: Unable to verify checksum for C:\Program Files\BOINC\boinc.exe
0012fb78 00430206 00000064 00424b3c 9999999a kernel32!Sleep+0xf
0012fb80 00424b3c 9999999a 3fb99999 00000002 boinc!boinc_sleep+0x16 [c:\boincsrc\main\boinc_public\lib\util.c @ 251]
0012fee0 00424f87 0012fefc 9999999a 3fb99999 boinc!NET_XFER_SET::do_select+0x26c [c:\boincsrc\main\boinc_public\client\net_xfer.c @ 319]
0012fef4 00407a2d 00000000 00000000 7c34f6f4 boinc!NET_XFER_SET::net_sleep+0x17 [c:\boincsrc\main\boinc_public\client\net_xfer.c @ 245]
0012ff18 004225dd 9999999a 3fb99999 00000000 boinc!CLIENT_STATE::net_sleep+0x7d [c:\boincsrc\main\boinc_public\client\client_state.c @ 369]
0012ff38 0042276f 7ffdf000 00000000 00000000 boinc!boinc_main_loop+0x7d [c:\boincsrc\main\boinc_public\client\main.c @ 331]
0012ff60 00431c0d 00000002 017acfc0 016def68 boinc!main+0x11f [c:\boincsrc\main\boinc_public\client\main.c @ 412]
0012ffc0 77e523cd 00000000 00000000 7ffdf000 boinc!mainCRTStartup+0x143 [f:\vs70builds\3077\vc\crtbld\crt\src\crtexe.c @ 398]
0012fff0 00000000 00431aca 00000000 78746341 kernel32!BaseProcessStart+0x23

Warning: You may need to add the BOINC directory to 'WinDBG.exe' symbol search path from the File menu in order to get a valid call stack.