process-tracker

Process tracker enables tracking creation of child processes.

Usage:

import process_tracker; process_tracker.install()

import os

pid1 = os.fork()
pid2 = os.fork()
pid3 = os.fork()

if pid1 and pid2 and pid3:
    print(process_tracker.children())

Prints a list of tuples with (pid, create_time) for each process.

create_time can be used to confirm that the current process (if any) with the given pid is the same as the original. For example:

import process_tracker
import psutil


def get_create_time(ctime):
    boot_time = psutil.boot_time()
    clock_ticks = os.sysconf("SC_CLK_TCK")
    return boot_time + (ctime / clock_ticks)


processes = []
for pid, create_time in process_tracker.children():
    try:
        p = psutil.Process(pid=pid)
    except psutil.NoSuchProcess:
        continue
    if p.create_time() == get_create_time(create_time):
        processes.append(p)

# processes now has the list of active child processes
# psutil itself does a check before sensitive operations that the
# active process create time is the same as when the Process object
# was initialized.
for p in processes:
    p.terminate()

Limitations

1. Only tracks children spawned from dynamically-linked executables.
2. Relies on LD_PRELOAD so will not work for setuid/setgid executables.

Development

Basic

1. python -m venv .venv
2. .venv/bin/python -m pip install tox
3. Make changes
4. .venv/bin/python -m tox

Debugging C build

Avoids overhead of making sdist

1. As above
2. make c-build

Debugging issues from sub-process

gdb debugging of sub-processes.

1. As above
2. make debug

Debugging tests without rebuild

1. As above
2. .venv/bin/python -m pip install . .[dev]

Then

• pip install . && pytest when rebuild is needed
• pytest when only tests changed

Release

docker run \
    -e REAL_UID=$(id -u) \
    -e REAL_GID=$(id -g) \
    -v "$PWD/scripts/build.sh:/build.sh" \
    -v "$PWD:/src" \
    dockcross/manylinux1-x64 \
    sh -c 'cd /src && env "PATH=/opt/python/cp37-cp37m/bin:$PATH" /build.sh'