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[udp] Register socket consumption for CONFIG_LWIP_MAX_SOCKETS#14068

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udp-consume-sockets
Feb 19, 2026
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[udp] Register socket consumption for CONFIG_LWIP_MAX_SOCKETS#14068
bdraco merged 2 commits intodevfrom
udp-consume-sockets

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@bdraco bdraco commented Feb 19, 2026 •
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What does this implement/fix?

The UDP component creates up to 2 sockets (broadcast_socket_ + listen_socket_) on ESP32 IDF but did not register them with the socket consumption API. This could cause CONFIG_LWIP_MAX_SOCKETS to be set too low, leading to socket exhaustion at runtime.

Note on SNTP: LWIP has two layers: raw PCBs (udp_new()/udp_sendto(), governed by CONFIG_LWIP_MAX_UDP_PCBS) and the BSD socket API (socket()/bind(), governed by CONFIG_LWIP_MAX_SOCKETS). The SNTP component calls esp_sntp_init() which internally uses a raw UDP PCB, not the socket API, so it does not consume from the socket pool and does not need socket registration.

Note on syslog: The syslog component uses its parent UDP component's socket, so it is already covered by this change.

Types of changes

  • Bugfix (non-breaking change which fixes an issue)
  • New feature (non-breaking change which adds functionality)
  • Breaking change (fix or feature that would cause existing functionality to not work as expected)
  • Developer breaking change (an API change that could break external components)
  • Code quality improvements to existing code or addition of tests
  • Other

Related issue or feature (if applicable):

Pull request in esphome-docs with documentation (if applicable):

  • N/A (internal fix, no user-facing changes)

Test Environment

  • ESP32
  • ESP32 IDF
  • ESP8266
  • RP2040
  • BK72xx
  • RTL87xx
  • LN882x
  • nRF52840

Example entry for config.yaml:

# No configuration changes needed - socket consumption is automatic
udp:
  port: 18511

Checklist:

  • The code change is tested and works locally.
  • Tests have been added to verify that the new code works (under tests/ folder).

If user exposed functionality or configuration variables are added/changed:

  • N/A - no user-facing changes

@bdraco
[udp] Register socket consumption for CONFIG_LWIP_MAX_SOCKETS
d814b0f 
The UDP component creates up to 2 sockets (broadcast + listen) but
did not register them with the socket consumption API. This could
cause CONFIG_LWIP_MAX_SOCKETS to be set too low on ESP32 IDF.

Closes #14031
Copilot AI review requested due to automatic review settings February 19, 2026 00:28
@bdraco bdraco requested a review from clydebarrow as a code owner February 19, 2026 00:28
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github-actions bot commented Feb 19, 2026

To use the changes from this PR as an external component, add the following to your ESPHome configuration YAML file:

external_components:
  - source: github://pr#14068
    components: [udp]
    refresh: 1h

(Added by the PR bot)

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github-actions bot commented Feb 19, 2026

👋 Hi there! I've automatically requested reviews from codeowners based on the files changed in this PR.

@clydebarrow - You've been requested to review this PR as codeowner(s) of 1 file(s) that were modified. Thanks for your time! 🙏

@bdraco bdraco added this to the 2026.2.1 milestone Feb 19, 2026
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codecov-commenter commented Feb 19, 2026 •
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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.11%. Comparing base (bd055e7) to head (2ddf46f).

Additional details and impacted files 
@@           Coverage Diff           @@
##              dev   #14068   +/-   ##
=======================================
  Coverage   74.11%   74.11%           
=======================================
  Files          55       55           
  Lines       11589    11589           
  Branches     1578     1578           
=======================================
  Hits         8589     8589           
  Misses       2598     2598           
  Partials      402      402

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

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@bdraco bdraco marked this pull request as draft February 19, 2026 00:30
Copilot AI reviewed Feb 19, 2026
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Pull request overview

Registers UDP component socket usage so ESP32 builds can correctly auto-size CONFIG_LWIP_MAX_SOCKETS, preventing runtime socket exhaustion (notably when UDP is used for syslog and similar features).

Changes:

  • Add a config-validation hook to register UDP’s worst-case socket consumption (2 sockets).
  • Wrap udp’s CONFIG_SCHEMA in cv.All(...) to run the socket consumer registration during validation.

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github-actions bot commented Feb 19, 2026

Memory Impact Analysis

Components: udp
Platform: esp8266-ard

Metric Target Branch This PR Change
RAM 29,240 bytes 29,240 bytes ➡️ +0 bytes (0.00%)
Flash 334,687 bytes 334,687 bytes ➡️ +0 bytes (0.00%)

Note: This analysis measures static RAM and Flash usage only (compile-time allocation).
Dynamic memory (heap) cannot be measured automatically.
⚠️ You must test this PR on a real device to measure free heap and ensure no runtime memory issues.

This analysis runs automatically when components change. Memory usage is measured from a representative test configuration.

@bdraco bdraco marked this pull request as ready for review February 19, 2026 00:45
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bdraco commented Feb 19, 2026

Thanks

@bdraco bdraco merged commit 5f82017 into dev Feb 19, 2026
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@bdraco bdraco deleted the udp-consume-sockets branch February 19, 2026 01:01
swoboda1337 pushed a commit that referenced this pull request Feb 20, 2026
@bdraco @swoboda1337
[udp] Register socket consumption for CONFIG_LWIP_MAX_SOCKETS (#14068)
8c0cc3a
@swoboda1337 swoboda1337 mentioned this pull request Feb 20, 2026
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@swoboda1337 swoboda1337 swoboda1337 approved these changes

@clydebarrow clydebarrow Awaiting requested review from clydebarrow clydebarrow is a code owner

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bugfix cherry-picked component: udp

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[esp32] Automatic CONFIG_LWIP_MAX_SOCKETS

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