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Disable initdb cancellation (#6451)

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## Problem

The initdb cancellation added in #5921 is not sufficient to reliably
abort the entire initdb process. Initdb also spawns children. The tests
added by #6310 (#6385) and #6436 now do initdb cancellations on a more
regular basis.

In #6385, I attempted to issue `killpg` (after giving it a new process
group ID) to kill not just the initdb but all its spawned subprocesses,
but this didn't work. Initdb doesn't take *that* long in the end either,
so we just wait until it concludes.

## Summary of changes

* revert initdb cancellation support added in #5921
* still return `Err(Cancelled)` upon cancellation, but this is just to
not have to remove the cancellation infrastructure
* fixes to the `test_tenant_delete_races_timeline_creation` test to make
it reliably pass

Fixes #6385
This commit is contained in:
Arpad Müller
2024-01-24 13:06:05 +01:00
committed by GitHub
parent 996abc9563
commit d820aa1d08
3 changed files with 46 additions and 26 deletions
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pageserver/src/tenant.rs
+17 -20
View File
@@ -91,7 +91,6 @@ use std::fs;
use std::fs::File;
use std::io;
use std::ops::Bound::Included;
use std::process::Stdio;
use std::sync::atomic::AtomicU64;
use std::sync::atomic::Ordering;
use std::sync::Arc;
@@ -3762,27 +3761,25 @@ async fn run_initdb(
.env_clear()
.env("LD_LIBRARY_PATH", &initdb_lib_dir)
.env("DYLD_LIBRARY_PATH", &initdb_lib_dir)
.stdout(Stdio::piped())
.stderr(Stdio::piped())
// If the `select!` below doesn't finish the `wait_with_output`,
// let the task get `wait()`ed for asynchronously by tokio.
// This means there is a slim chance we can go over the INIT_DB_SEMAPHORE.
// TODO: fix for this is non-trivial, see
// https://github.com/neondatabase/neon/pull/5921#pullrequestreview-1750858021
//
.kill_on_drop(true)
.spawn()?;
tokio::select! {
initdb_output = initdb_command.wait_with_output() => {
let initdb_output = initdb_output?;
if !initdb_output.status.success() {
return Err(InitdbError::Failed(initdb_output.status, initdb_output.stderr));
}
}
_ = cancel.cancelled() => {
return Err(InitdbError::Cancelled);
}
// Ideally we'd select here with the cancellation token, but the problem is that
// we can't safely terminate initdb: it launches processes of its own, and killing
// initdb doesn't kill them. After we return from this function, we want the target
// directory to be able to be cleaned up.
// See https://github.com/neondatabase/neon/issues/6385
let initdb_output = initdb_command.wait_with_output().await?;
if !initdb_output.status.success() {
return Err(InitdbError::Failed(
initdb_output.status,
initdb_output.stderr,
));
}
// This isn't true cancellation support, see above. Still return an error to
// excercise the cancellation code path.
if cancel.is_cancelled() {
return Err(InitdbError::Cancelled);
}
Ok(())