lcm

library1.5.2pypypi✓ verified 90d ago

lcm (Lightweight Communication and Marshalling) is a library for interprocess communication with real-time constraints, providing a low-latency publish/subscribe message passing model. Version 1.5.2 supports Python >=3.7. Release cadence is irregular, typically yearly.

serialization http-networking communication

pip install lcm

package ↗homepage ↗

INSTALL

IMPORT

SIG · LCM

lcm

serializationpythonv1.5.2

Install

1.6s avg

Import

28ms

Disk

20MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v1.5.2 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.95 runs

installs and imports cleanly · install 0.0s · import 0.028s · 21.9MB

glibc

py 3.10–3.95 runs

installs and imports cleanly · install 1.6s · import 0.000s · 22MB

20MB installed

● package 20MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

LCM

✓ from lcm import LCM

✗ import lcm

Common mistake: using 'import lcm' gives you the module object, not the class. 'from lcm import LCM' is required to access the main class.

EventLog

✓ from lcm import EventLog

Initialize LCM, subscribe to a channel, handle incoming messages, and publish a test message.

from lcm import LCM lc = LCM() def handler(channel, data): print(f"Received on {channel}: {data}") lc.subscribe("EXAMPLE_CHANNEL", handler) lc.handle() lc.publish("EXAMPLE_CHANNEL", b"Hello, world!")

lcm-gen --version

Debug

Known issues

gotchalcm requires a running LCM daemon (lcm-logger or similar) or multicast network. Without it, publish/subscribe silently fails.

fix

Ensure LCM daemon is running or network multicast is configured. Test with lcm-spy or a simple sender/receiver.

affects: all

gotchaThe LCM class is not thread-safe. Calling methods from multiple threads can cause undefined behavior.

fix

Use locking mechanisms or ensure all LCM calls happen from a single thread.

affects: all

gotchaLCM messages are raw bytes; data serialization is left to the user. There's no built-in type marshalling beyond bytes.

fix

Use struct.pack/unpack, protobuf, or similar for structured data. Example: data = struct.pack('i', 42).

affects: all

Errors

Common errors & fixes

ModuleNotFoundError: No module named 'lcm'

lcm not installed or installed in wrong environment.

fix

Run: pip install lcm

AttributeError: module 'lcm' has no attribute 'LCM'

Imported as 'import lcm' instead of 'from lcm import LCM'.

fix

Use: from lcm import LCM

OSError: [Errno 19] No such device

LCM tries to open multicast socket but network interface doesn't support multicast or is missing.

fix

Check network configuration, or use LCM with a directed UDP address. On Linux, ensure multicast is enabled: sudo apt-get install net-tools && route -n

Upgrade

Version history

1.5.2latest on PyPI · released Oct 23, 2025

Audit

Dependencies

No dependency data recorded yet.

Agent activity

29 hits · last 30 days

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Resources

packagehttps://pypi.org/project/lcm/ ↗

homepagehttps://lcm-proj.github.io ↗