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Code Issues Packages 1 Wiki Activity

perf: fairer ops scheduling (#3128)

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This commit is contained in:
Bartek Iwańczuk 2019-10-15 23:12:27 +02:00 committed by Bert Belder
parent ddbfe9b5aa
commit 54db12c4d9
1 changed files with 21 additions and 11 deletions
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32
core/isolate.rs
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@ -158,6 +158,7 @@ pub struct Isolate {
have_unpolled_ops: bool,
startup_script: Option<OwnedScript>,
op_registry: OpRegistry,
eager_poll_count: u32,
}
unsafe impl Send for Isolate {}
@ -223,6 +224,7 @@ impl Isolate {
pending_dyn_imports: FuturesUnordered::new(),
startup_script,
op_registry: OpRegistry::new(),
eager_poll_count: 0,
}
}
@ -315,19 +317,26 @@ impl Isolate {
PinnedBuf::new(zero_copy_buf),
);
let op = match op {
Op::Async(mut fut) => {
// Tries to greedily poll async ops once. Often they are immediately ready, in
// which case they can be turned into a sync op before we return to V8. This
// can save a boundary crossing.
#[allow(clippy::match_wild_err_arm)]
match fut.poll() {
Err(_) => panic!("unexpected op error"),
Ok(Ready(buf)) => Op::Sync(buf),
Ok(NotReady) => Op::Async(fut),
// To avoid latency problems we eagerly poll 50 futures and then
// allow to poll ops from `pending_ops`
let op = if isolate.eager_poll_count != 50 {
isolate.eager_poll_count += 1;
match op {
Op::Async(mut fut) => {
// Tries to eagerly poll async ops once. Often they are immediately ready, in
// which case they can be turned into a sync op before we return to V8. This
// can save a boundary crossing.
#[allow(clippy::match_wild_err_arm)]
match fut.poll() {
Err(_) => panic!("unexpected op error"),
Ok(Ready(buf)) => Op::Sync(buf),
Ok(NotReady) => Op::Async(fut),
}
}
Op::Sync(buf) => Op::Sync(buf),
}
Op::Sync(buf) => Op::Sync(buf),
} else {
op
};
debug_assert_eq!(isolate.shared.size(), 0);
@ -647,6 +656,7 @@ impl Future for Isolate {
// Now handle actual ops.
self.have_unpolled_ops = false;
self.eager_poll_count = 0;
#[allow(clippy::match_wild_err_arm)]
match self.pending_ops.poll() {
Err(_) => panic!("unexpected op error"),