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66b0bf41a1
While investigating Pageserver logs from the cases where systemd hangs during shutdown (https://github.com/neondatabase/cloud/issues/11387), I noticed that even if Pageserver shuts down cleanly[^1], there are lingering walredo processes. [^1]: Meaning, pageserver finishes its shutdown procedure and calls `exit(0)` on its own terms, instead of hitting the systemd unit's `TimeoutSec=` limit and getting SIGKILLed. While systemd should never lock up like it does, maybe we can avoid hitting that bug by cleaning up properly. Changes ------- This PR adds a shutdown method to `WalRedoManager` and hooks it up to tenant shutdown. We keep track of intent to shutdown through the new `enum ProcessOnceCell` stored inside the pre-existing `redo_process` field. A gate is added to keep track of running processes, using the new type `struct Process`. Future Work ----------- Requests that don't need the redo process will not observe the shutdown (see doc comment). Doing so would be nice for completeness sake, but doesn't provide much benefit because `Tenant` and `Timeline` already shut down all walredo users. Testing ------- I did manual testing to confirm that the problem exists before this PR and that it's gone after. Setup: * `neon_local` with a single tenant, create some data using `pgbench` * ensure walredo process is running, not pid * watch `strace -e kill,wait4 -f -p "$(pgrep pageserver)"` * `neon_local pageserver stop` With this PR, we always observe ``` $ strace -e kill,wait4 -f -p "$(pgrep pageserver)" ... [pid 591120] --- SIGTERM {si_signo=SIGTERM, si_code=SI_USER, si_pid=591215, si_uid=1000} --- [pid 591134] kill(591174, SIGKILL) = 0 [pid 591134] wait4(591174, <unfinished ...> [pid 591142] --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_KILLED, si_pid=591174, si_uid=1000, si_status=SIGKILL, si_utime=0, si_stime=0} --- [pid 591134] <... wait4 resumed>[{WIFSIGNALED(s) && WTERMSIG(s) == SIGKILL}], 0, NULL) = 591174 ... +++ exited with 0 +++ ``` Before this PR, we'd usually observe just ``` ... [pid 596239] --- SIGTERM {si_signo=SIGTERM, si_code=SI_USER, si_pid=596455, si_uid=1000} --- ... +++ exited with 0 +++ ``` Refs ---- refs https://github.com/neondatabase/cloud/issues/11387
Pageserver Benchmarks
How to run
To run all benchmarks:
cargo bench
To run a specific file:
cargo bench --bench bench_layer_map
To run a specific function:
cargo bench --bench bench_layer_map -- real_map_uniform_queries