snapshot of https://github.com/zulip/zulip.git @ 48c69911c7dd4e03b20552eb3bd77ad8151c1357 (2026-09-15)

zerver/lib/debug.py

@@ -0,0 +1,117 @@
+import code
+import gc
+import logging
+import os
+import signal
+import socket
+import threading
+import traceback
+import tracemalloc
+from types import FrameType
+
+from django.conf import settings
+from django.utils.timezone import now as timezone_now
+
+logger = logging.getLogger("zulip.debug")
+
+
+# Interactive debugging code from
+# https://stackoverflow.com/questions/132058/showing-the-stack-trace-from-a-running-python-application
+# (that link also points to code for an interactive remote debugger
+# setup, which we might want if we move Tornado to run in a daemon
+# rather than via screen).
+def interactive_debug(sig: int, frame: FrameType | None) -> None:
+    """Interrupt running process, and provide a python prompt for
+    interactive debugging."""
+    d = {"_frame": frame}  # Allow access to frame object.
+    if frame is not None:
+        d.update(frame.f_globals)  # Unless shadowed by global
+        d.update(frame.f_locals)
+
+    message = "Signal received : entering python shell.\nTraceback:\n"
+    message += "".join(traceback.format_stack(frame))
+    i = code.InteractiveConsole(d)
+    i.interact(message)
+
+
+# SIGUSR1 => Just print the stack
+# SIGUSR2 => Print stack + open interactive debugging shell
+def interactive_debug_listen() -> None:
+    signal.signal(signal.SIGUSR1, lambda sig, stack: traceback.print_stack(stack))
+    signal.signal(signal.SIGUSR2, interactive_debug)
+
+
+def tracemalloc_dump() -> None:
+    if not tracemalloc.is_tracing():
+        logger.warning("pid %s: tracemalloc off, nothing to dump", os.getpid())
+        return
+    # Despite our name for it, `timezone_now` always deals in UTC.
+    basename = "snap.{}.{}".format(
+        os.getpid(), timezone_now().replace(tzinfo=None).isoformat("-", "seconds")
+    )
+    path = os.path.join(settings.TRACEMALLOC_DUMP_DIR, basename)
+    os.makedirs(settings.TRACEMALLOC_DUMP_DIR, exist_ok=True)
+
+    gc.collect()
+    tracemalloc.take_snapshot().dump(path)
+
+    with open(f"/proc/{os.getpid()}/stat", "rb") as f:
+        procstat = f.read().split()
+    rss_pages = int(procstat[23])
+    logger.info(
+        "tracemalloc dump: tracing %s MiB (%s MiB peak), using %s MiB; rss %s MiB; dumped %s",
+        tracemalloc.get_traced_memory()[0] // 1048576,
+        tracemalloc.get_traced_memory()[1] // 1048576,
+        tracemalloc.get_tracemalloc_memory() // 1048576,
+        rss_pages // 256,
+        basename,
+    )
+
+
+def tracemalloc_listen_sock(sock: socket.socket) -> None:
+    logger.debug("pid %s: tracemalloc_listen_sock started!", os.getpid())
+    while True:
+        sock.recv(1)
+        tracemalloc_dump()
+
+
+listener_pid: int | None = None
+
+
+def tracemalloc_listen() -> None:
+    global listener_pid
+    if listener_pid == os.getpid():
+        # Already set up -- and in this process, not just its parent.
+        return
+    logger.debug("pid %s: tracemalloc_listen working...", os.getpid())
+    listener_pid = os.getpid()
+
+    sock = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
+    os.makedirs(settings.TRACEMALLOC_DUMP_DIR, exist_ok=True)
+    path = os.path.join(settings.TRACEMALLOC_DUMP_DIR, f"tracemalloc.{os.getpid()}")
+    sock.bind(path)
+    thread = threading.Thread(target=lambda: tracemalloc_listen_sock(sock), daemon=True)
+    thread.start()
+    logger.debug("pid %s: tracemalloc_listen done: %s", os.getpid(), path)
+
+
+def maybe_tracemalloc_listen() -> None:
+    """If tracemalloc tracing enabled, listen for requests to dump a snapshot.
+
+    To trigger once this is listening:
+      echo | socat -u stdin unix-sendto:/var/log/zulip/tracemalloc/tracemalloc.$pid
+
+    To enable in the Zulip web server: edit /etc/zulip/uwsgi.ini ,
+    and add e.g. ` PYTHONTRACEMALLOC=5` to the `env=` line.
+    This function is called in middleware, so the process will
+    automatically start listening.
+
+    To enable in other contexts: see upstream docs
+    https://docs.python.org/3/library/tracemalloc .
+    You may also have to add a call to this function somewhere.
+
+    """
+    if os.environ.get("PYTHONTRACEMALLOC"):
+        # If the server was started with `tracemalloc` tracing on, then
+        # listen for a signal to dump `tracemalloc` snapshots.
+        tracemalloc_listen()