gh-145411: Add runtime (now: `unix` only) control to Tachyon by maurycy · Pull Request #149958 · python/cpython

maurycy · 2026-05-17T19:33:42Z

Only unix: for starters:

Control socket:
  --control URI         control socket URI (unix:<path>) (default: None)

Supported commands are enable, disable, ping, status and quit. Each command is confirmed with either ok or err.

Example session:

[1] 2026-05-17T21:18:38.400172000+0200 maurycy@gimel /Users/maurycy/src/github.com/maurycy/cpython (tachyon-runtime-socket ed77e71) % sudo -E ./python.exe -m profiling.sampling run --control unix:/tmp/tachyon.sock -r 666khz -m test test_asyncio &>/dev/null &
[1] 84494
2026-05-17T21:18:41.130015000+0200 maurycy@gimel /Users/maurycy/src/github.com/maurycy/cpython (tachyon-runtime-socket ed77e71) % echo -e 'ping' | sudo nc -U /tmp/tachyon.sock
ok
2026-05-17T21:18:42.759758000+0200 maurycy@gimel /Users/maurycy/src/github.com/maurycy/cpython (tachyon-runtime-socket ed77e71) % echo -e 'status' | sudo nc -U /tmp/tachyon.sock
ok enabled=True 
2026-05-17T21:18:44.875693000+0200 maurycy@gimel /Users/maurycy/src/github.com/maurycy/cpython (tachyon-runtime-socket ed77e71) % echo -e 'enable' | sudo nc -U /tmp/tachyon.sock
ok
2026-05-17T21:18:46.871140000+0200 maurycy@gimel /Users/maurycy/src/github.com/maurycy/cpython (tachyon-runtime-socket ed77e71) % echo -e 'disable' | sudo nc -U /tmp/tachyon.sock
ok
2026-05-17T21:18:48.756932000+0200 maurycy@gimel /Users/maurycy/src/github.com/maurycy/cpython (tachyon-runtime-socket ed77e71) % echo -e 'enable' | sudo nc -U /tmp/tachyon.sock
ok
2026-05-17T21:18:49.083766000+0200 maurycy@gimel /Users/maurycy/src/github.com/maurycy/cpython (tachyon-runtime-socket ed77e71) % echo -e 'zażółć gęślą jaźn' | sudo nc -U /tmp/tachyon.sock
err unknown_command
2026-05-17T21:18:50.670507000+0200 maurycy@gimel /Users/maurycy/src/github.com/maurycy/cpython (tachyon-runtime-socket ed77e71) % echo -e 'quit' | sudo nc -U /tmp/tachyon.sock
ok
[1]  + done       sudo -E ./python.exe -m profiling.sampling run --control  -r 666khz -m test

Closes #149958

Issue: Add runtime control for profiling.sampling #145411

maurycy · 2026-05-17T19:35:01Z

+        if conn in self._connections:
+            self._flush_connection(conn)
+
+    def _dispatch(self, conn, command):


No dump / snapshot yet.

maurycy · 2026-05-17T19:36:49Z

+    if getattr(args, 'control', None) is not None:
+        if args.subprocesses:
+            parser.error("--control is incompatible with --subprocesses.")
+        if os.name == "nt":


Unfortunately, I don't have access to Windows.

maurycy · 2026-05-17T19:37:15Z


+    if getattr(args, 'control', None) is not None:
+        if args.subprocesses:
+            parser.error("--control is incompatible with --subprocesses.")


@pablogsal Proper communication with children would be very complex. Maybe we can just use signals for enabling and disabling them.

maurycy · 2026-05-17T19:37:51Z

+from .errors import ControlError, ControlURIError
+
+
+class ProfilerControl:


I did not want to inject this into LiveCollector but the direction is clear.

maurycy · 2026-05-17T19:38:40Z

cc @pablogsal @ivonastojanovic @lkollar

maurycy · 2026-05-17T19:59:55Z


-    with _get_child_monitor_context(args, args.pid):
+    server = None
+    with ExitStack() as stack:


Keeping should-be-soon-to-be-added signal (SIGUSR1, SIGUSR2 for enabling or disabling?) support in mind.

lkollar · 2026-05-18T18:30:06Z

+        self.close_after_write = False
+
+
+class ControlServer:


Thanks for the PR @maurycy, this looks really interesting. I think we should introduce an abstraction here to be able to implement other transport protocols. Most importantly, I think we will need named pipes on Windows, but it would also allow things like adding TCP transport later down the line.

I spoke with @pablogsal briefly about this and we agreed that ideally we'd have Windows support also included in this change. Do you think you could look into that? I can run Windows in a VM and may be able to help out, but I'm not sure when I'll be able to get around to it.

+1 on the abstraction, it would be great to have everything here. I’d also love to see the snapshot command in this change.

here goes my sunday

ed77e71

maurycy requested a review from pablogsal as a code owner May 17, 2026 19:33

bedevere-app Bot added the awaiting review label May 17, 2026

bedevere-app Bot mentioned this pull request May 17, 2026

Add runtime control for profiling.sampling #145411

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maurycy commented May 17, 2026

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maurycy changed the title ~~gh-145411: Add socket control to Tachyon~~ gh-145411: Add runtime (now: unix only) control to Tachyon May 17, 2026

maurycy added 3 commits May 17, 2026 21:48

blurb

1bc72ec

skip sample_interval_usec in v0

71c6b97

from ... contextlib

0fe9ad1

maurycy commented May 17, 2026

View reviewed changes

maurycy and others added 3 commits May 17, 2026 22:01

accidentially removed comment

005098d

fix ci

63447d3

after sleeping over: 1-100ms latency here is ok

20bc76b

lkollar reviewed May 18, 2026

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gh-145411: Add runtime (now: `unix` only) control to Tachyon#149958

gh-145411: Add runtime (now: `unix` only) control to Tachyon#149958
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maurycy:tachyon-runtime-socket

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		from .errors import ControlError, ControlURIError


		class ProfilerControl:

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