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diff --git a/docs/parsing_stack_traces.md b/docs/parsing_stack_traces.md new file mode 100644 index 00000000000..84dd8b3cd34 --- /dev/null +++ b/docs/parsing_stack_traces.md @@ -0,0 +1,63 @@ +# Parsing Stack Traces + +## `addr2line` + +[`addr2line`][1] is a utility to translate addresses into filenames and line numbers. + +``` +addr2line -e mongod -ifC <offset> +``` + + +## `c++filt` + +Use [`c++filt`][2] to demangle function names by pasting the whole stack trace to stdin. + + +## Finding the Right Binary + +To find the correct binary for a specific log you need to: + +1. Get the commit from the header of the logs. +2. Use git to locate that commit and check for the surrounding "version bump" commit. +3. Download and open the binary: + +``` +curl -O http://s3.amazonaws.com/downloads.mongodb.org/linux/mongodb-linux-x86_64-debugsymbols-1.x.x.tgz +``` + +You can also get the debugsymbols archive for official builds through [the Downloads page][3]. In the +Archived Releases section, click on the appropriate platform link to view the available archives. +Select the appropriate debug symbols archive. + +### Example: Reading the Log + +Note that the log has lines like this: + +``` +/home/abc/mongod(_ZN5mongo15printStackTraceERSo+0x27) [0x689280] +``` + +You want to use the address in between the brackets `0x689280`. Note that you will get more than one +stack frame for the address if the code is inlined. + +### Example: Using `addr2line` + +Actual example from a v1.8.1 64-bit Linux build: + +``` +$ curl http://downloads.mongodb.org/linux/mongodb-linux-x86_64-debugsymbols-1.8.1.tgz > out.tgz +$ tar -xzf out.tgz +$ cd mongodb-linux-x86_64-debugsymbols-1.8.1/ +$ cd bin +$ addr2line --help +$ addr2line -i -e mongod 0x6d6a74 +/mnt/home/buildbot/slave/Linux_64bit_V1.8/mongo/db/repl/health.cpp:394 +$ addr2line -i -e mongod 0x6d0694 +/mnt/home/buildbot/slave/Linux_64bit_V1.8/mongo/db/repl/rs.h:385 +/mnt/home/buildbot/slave/Linux_64bit_V1.8/mongo/db/repl/replset_commands.cpp:111 +``` + +[1]: https://sourceware.org/binutils/docs/binutils/addr2line.html +[2]: https://sourceware.org/binutils/docs-2.17/binutils/c_002b_002bfilt.html +[3]: https://www.mongodb.com/download-center |