bjoernager/rust
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Auto merge of #98570 - SparrowLii:deadlock, r=cjgillot

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get rid of `tcx` in deadlock handler when parallel compilation

This is a very obscure and hard-to-trace problem that affects thread scheduling. If we copy `tcx` to the deadlock handler thread, it will perform unpredictable behavior and cause very weird problems when executing `try_collect_active_jobs`(For example, the deadlock handler thread suddenly preempts the content of the blocked worker thread and executes the unknown judgment branch, like #94654).
Fortunately we can avoid this behavior by precomputing `query_map`. This change fixes the following ui tests failure on my environment when set `parallel-compiler = true`:
```
    [ui] src/test\ui\async-await\no-const-async.rs
    [ui] src/test\ui\infinite\infinite-struct.rs
    [ui] src/test\ui\infinite\infinite-tag-type-recursion.rs
    [ui] src/test\ui\issues\issue-3008-1.rs
    [ui] src/test\ui\issues\issue-3008-2.rs
    [ui] src/test\ui\issues\issue-32326.rs
    [ui] src/test\ui\issues\issue-57271.rs
    [ui] src/test\ui\issues\issue-72554.rs
    [ui] src/test\ui\parser\fn-header-semantic-fail.rs
    [ui] src/test\ui\union\union-nonrepresentable.rs
```

Updates #75760
Fixes #94654
This commit is contained in:
bors 2022-07-03 02:05:14 +00:00
commit 8c52a83c45
4 changed files with 9 additions and 21 deletions
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20
compiler/rustc_interface/src/util.rs
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@ -10,7 +10,7 @@ use rustc_errors::registry::Registry;
use rustc_middle::ty::tls;
use rustc_parse::validate_attr;
#[cfg(parallel_compiler)]
use rustc_query_impl::QueryCtxt;
use rustc_query_impl::{QueryContext, QueryCtxt};
use rustc_session as session;
use rustc_session::config::CheckCfg;
use rustc_session::config::{self, CrateType};
@ -166,20 +166,12 @@ pub fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
unsafe fn handle_deadlock() {
let registry = rustc_rayon_core::Registry::current();
let context = tls::get_tlv();
assert!(context != 0);
rustc_data_structures::sync::assert_sync::<tls::ImplicitCtxt<'_, '_>>();
let icx: &tls::ImplicitCtxt<'_, '_> = &*(context as *const tls::ImplicitCtxt<'_, '_>);
let session_globals = rustc_span::with_session_globals(|sg| sg as *const _);
let session_globals = &*session_globals;
thread::spawn(move || {
tls::enter_context(icx, |_| {
rustc_span::set_session_globals_then(session_globals, || {
tls::with(|tcx| QueryCtxt::from_tcx(tcx).deadlock(&registry))
})
});
let query_map = tls::with(|tcx| {
QueryCtxt::from_tcx(tcx)
.try_collect_active_jobs()
.expect("active jobs shouldn't be locked in deadlock handler")
});
thread::spawn(move || rustc_query_impl::deadlock(query_map, &registry));
}
#[cfg(parallel_compiler)]