Print thread name when dumping backtrace #6
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Keeping proc interactions isoltated: added function in proc.h/.c that prints thread name to stdout. It is then used by backtrace.c directly to keep from having to store the string in memory in snapshot or any other struct
src/proc.c
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| int print_proc_comm(int pid) | ||
| { | ||
| FILE *f; | ||
| char buf[32] = ""; |
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Is this initialization really needed?
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I believe an earlier implementation required it. It's probably not needed now, however, I feel safer making sure a string is properly terminated.
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Let me know your thoughts on the new commits. I wasn't able to center the text but I at least squared it up better. |
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Any thoughts on the recent changes? |
| if (x > 0 && x <= sizeof(end_pad)) | ||
| { | ||
| end_pad[sizeof(end_pad) - x] = '\0'; | ||
| printf("-------------- thread %d (%d) (%s) %s\n", (index != NULL ? index[i] : i+1), snap->tids[i], comm, end_pad); |
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If get_thread_num() fails for some reason, or the name is too long, the header is not printed at all. This is quite wrong. In case of error it should be indicated in some simple way (like we do when a file is deleted). If the name is too long, we can truncate it.
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@nslowell sorry for missing your updates. I did some review, see my new comment. |
src/backtrace.c
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| printf("-------------------- thread %d (%d) --------------------\n", | ||
| printf("-------------------- thread %d (%d) (", | ||
| (index != NULL ? index[i] : i+1), threads[i]); | ||
| print_proc_comm(threads[i]); |
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Is it a good idea to call print_proc_comm here, while the process is stopped?
As print_proc_comm is currently implemented it opens, reads, and closes the comm file for each thread.
In a large server process with thousands of threads, this will add noticeably to the time frozen.
Why not collect the thread names before the call to attach_process(), the same way thread states are handled, then pass the thread name for the current thread to print_thread_heading?
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Keeping proc interactions isoltated: added function in proc.h/.c
that prints thread name to stdout. It is then used by backtrace.c
directly to keep from having to store the string in memory in
snapshot or any other struct