| | 1 | = Debugging server components = |
| | 2 | |
| | 3 | A grab-bag of techniques for debugging BOINC server software: |
| | 4 | |
| | 5 | |
| | 6 | == Log files == |
| | 7 | Most error conditions are reported in the log files. Make sure you know where these are. If you're interested in the history of a particular WU or result, grep for WU#12345 or RESULT#12345 (12345 represents the ID) in the log files. The html/ops pages also provide an interface for this. |
| | 8 | == Database query tracing == |
| | 9 | If you uncomment the symbol SHOW_QUERIES in db/db_base.C, and recompile everything, all database queries will be written to stderr (for daemons, this goes to log files; for command-line apps it's written to your terminal). This is verbose but extremely useful for tracking down database-level problems. |
| | 10 | == Getting core dumps from the scheduler == |
| | 11 | In sched/main.C put: |
| | 12 | |
| | 13 | |
| | 14 | {{{ |
| | 15 | #define DUMP_CORE_ON_SEGV 1 |
| | 16 | }}} |
| | 17 | and recompile. |
| | 18 | == Running the scheduler under a debugger == |
| | 19 | The scheduler is a CGI program. It reads from stdin and writes to stdout, so you can also run it with a command-line debugger like gdb: |
| | 20 | * Copy the "scheduler_request_X.xml" file from a client to the machine running the scheduler. (X = your project URL) |
| | 21 | * Run the scheduler under the debugger, giving it this file as stdin, i.e.: |
| | 22 | {{{ |
| | 23 | gdb cgi |
| | 24 | (set a breakpoint) |
| | 25 | r < scheduler_request_X.xml |
| | 26 | }}} |
| | 27 | * You may have to doctor the database as follows: |
| | 28 | {{{ |
| | 29 | update host set rpc_seqno=0, rpc_time=0 where hostid=N |
| | 30 | }}} |
| | 31 | to keep the scheduler from rejecting the request. |
| | 32 | |
| | 33 | This is useful for figuring out why your project is generating 'no work available' messages. As an alternative to this, edit handle_request.C, and put a call to debug_sched(sreq, sreply, "../debug_sched") just before sreply.write(fout). Then, after recompiling, touch a file called 'debug_sched' in the project root directory. This will cause transcripts of all subsequent scheduler requests and replies to be written to the cgi-bin/ directory with separate small files for each request. The file names are sched_request_H_R where H=hostid and R=rpc sequence number. This can be turned off by deleting the 'debug_sched' file. |
| | 34 | == MySQL interfaces == |
| | 35 | You should become familiar with MySQL tools such as |
| | 36 | * mytop: like 'top' for MySQL |
| | 37 | * the mysql interpreter ('mysql') and in particular the 'show processlist;' query. |
| | 38 | * MySQLadmin: general-purpose web interface to MySQL |
| | 39 | |
