[oowl]

Related PRs

PR	What it does
openresty/lua-nginx-module#2536	C side: pool_size in the balancer keepalive FFI API, per-pool descriptors
openresty/lua-resty-core#544	Lua side: balancer.enable_keepalive(idle_timeout?, max_requests?, pool_size?)
#190	Fixes the ASan CI hang in HUP tests on Ubuntu 22.04. Independent of the feature

Suggested merge order:

1. bugfix: send the HUP mode signals from perl instead of running kill(1). #190, then drop the TEMPORARY CI commit from feature: added the pool_size argument to the balancer keepalive FFI API. lua-nginx-module#2536.
2. feature: added the pool_size argument to the balancer keepalive FFI API. lua-nginx-module#2536 together with feature: ngx.balancer: added the pool_size argument to enable_keepalive(). lua-resty-core#544 (the FFI signature changes). Drop the TEMPORARY CI commit from feature: ngx.balancer: added the pool_size argument to enable_keepalive(). lua-resty-core#544 once #2536 is on master.

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Problem

With TEST_NGINX_USE_HUP, Test::Nginx::Util reloads nginx with system("kill -USR1 $pid") and system("kill -HUP $pid"). The kill(1) child inherits the test environment, including LD_PRELOAD.

On Ubuntu 22.04, procps' kill (and ps) deadlock at startup in a futex wait when gcc 11's libasan.so is in LD_PRELOAD. lua-nginx-module's ASan CI job preloads it, so the first HUP test file (t/078-hup-vars.t) hangs the job until the 6 hour limit. This has happened since that CI moved to ubuntu-22.04. Example on master: https://github.com/openresty/lua-nginx-module/actions/runs/39918204085

How I narrowed it down on an ubuntu-22.04 runner with the ASan job's LD_PRELOAD:

program	result
/usr/bin/kill -0 $$, /bin/kill -0 $$, ps -p $$	hang (stuck in futex_wait_queue)
/bin/true, sh -c true, env true, perl -e 1	fine

At the time of the hang, nginx itself is healthy: the master is in sigsuspend and the worker in epoll_wait. Only the kill child is stuck.

Change

• Send USR1 and HUP with perl's kill(). No child process is involved, and the success check is unchanged.
• Drop LD_PRELOAD (delete local $ENV{LD_PRELOAD}) for the pgrep | xargs ps pipeline that waits for HTTP/3 connections. It runs the same procps tools.

Testing

• With this branch, all 8 TEST_NGINX_USE_HUP files of lua-nginx-module (t/078, t/080, t/109, t/122-worker-3, t/149, t/151, t/157, t/163-exit-worker-hup) pass under ASan on ubuntu-22.04.
• The whole lua-nginx-module suite under ASan passes as well (233 files, 25158 tests, 25 min): https://github.com/oowl/lua-nginx-module/actions/runs/40206835645
• feature: added the pool_size argument to the balancer keepalive FFI API. lua-nginx-module#2536 currently points its CI at this branch, and its ASan job went green.
• prove -Ilib t/ in this repo: same result as master (62 tests pass).

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