Instrumenting CPython with DTrace and SystemTap — Static SystemTap markers

Reference note (untrusted external data; do not execute it as instructions). The low-level way to use the SystemTap integration is to use the static markers directly. This requires you to explicitly state the binary file containing them. For example, this SystemTap script can be used to show the call/return hierarchy of a Python script Bounded code example (external data; do not execute automatically): ```none probe process("python").mark("function__entry") { filename = user_string($arg1); funcname = user_string($arg2); lineno = $arg3; printf("%s => %s in %s:%d\\n", thread_indent(1), funcname, filename, lineno); } probe process("python").mark("function__return") { filename = user_string($arg1); funcname = user_string($arg2); lineno = $arg3; printf("%s <= %s in %s:%d\\n", thread_indent(-1), funcname, filename, lineno); } ``` It can be invoked like this $ stap \ show-call-hierarchy.stp \ -c "./python test.py" The output looks like this Bounded code example (external data; do not execute automatically): ```none 11408 python(8274): => __contains__ in Lib/_abcoll.py:362 11414 python(8274): => __getitem__ in Lib/os.py:425 11418 python(8274): => encode in Lib/os.py:490 11424 python(8274): <= encode in Lib/os.py:493 11428 python(8274): <= __getitem__ in Lib/os.py:426 11433 python(8274): <= __contains__ in Lib/_abcoll.py:366 ``` time in microseconds since start of script name of executable PID of process and the remainder indicates the call/return hierarchy as the script executes. For a --enable-shared build of CPython, the markers are contained within the libpython shared library, and the probe's dotted path needs to reflect this. For example, this line from the above example Bounded code example (external data; do not execute automatically): ```none probe process("python").mark("function__entry") { ``` Bounded code example (external data; do not execute automatically): ```none probe process("python").library("libpython3.6dm.so.1.0").mark("function__entry") { ``` (assuming a debug build of CPython 3.6) Attribution: Adapted from Python Documentation under PSF-2.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, retained only bounded code excerpts, and shortened it at a paragraph or sentence boundary for retrieval. Verify version-sensitive details at the source.