Unverified Commit ee1b80aa authored by Chris Sosnin's avatar Chris Sosnin Committed by GitHub
Browse files

Move artifacts states into memory in PVF validation host (#3907)



* pvf host: store only compiled artifacts on disk

* Correctly handle failed artifacts

* Serialize result of PVF preparation uniquely

* Set the artifact state depending on the result

* Return the result of PVF preparation directly

* Move PrepareError to the error module

* Update doc comments

* Update misleading comment

* Cleanup docs

* Conclude a test job with an error

Co-authored-by: Sergey Pepyakin's avatarSergei Shulepov <sergei@parity.io>
parent fc32642c
Pipeline #163452 passed with stages
in 52 minutes and 31 seconds
......@@ -14,6 +14,7 @@
// You should have received a copy of the GNU General Public License
// along with Polkadot. If not, see <http://www.gnu.org/licenses/>.
use crate::error::PrepareError;
use always_assert::always;
use async_std::path::{Path, PathBuf};
use parity_scale_codec::{Decode, Encode};
......@@ -23,30 +24,19 @@ use std::{
time::{Duration, SystemTime},
};
/// A final product of preparation process. Contains either a ready to run compiled artifact or
/// a description what went wrong.
/// A wrapper for the compiled PVF code.
#[derive(Encode, Decode)]
pub enum Artifact {
/// During the prevalidation stage of preparation an issue was found with the PVF.
PrevalidationErr(String),
/// Compilation failed for the given PVF.
PreparationErr(String),
/// This state indicates that the process assigned to prepare the artifact wasn't responsible
/// or were killed. This state is reported by the validation host (not by the worker).
DidntMakeIt,
/// The PVF passed all the checks and is ready for execution.
Compiled { compiled_artifact: Vec<u8> },
}
pub struct CompiledArtifact(Vec<u8>);
impl Artifact {
/// Serializes this struct into a byte buffer.
pub fn serialize(&self) -> Vec<u8> {
self.encode()
impl CompiledArtifact {
pub fn new(code: Vec<u8>) -> Self {
Self(code)
}
}
/// Deserialize the given byte buffer to an artifact.
pub fn deserialize(mut bytes: &[u8]) -> Result<Self, String> {
Artifact::decode(&mut bytes).map_err(|e| format!("{:?}", e))
impl AsRef<[u8]> for CompiledArtifact {
fn as_ref(&self) -> &[u8] {
self.0.as_slice()
}
}
......@@ -117,6 +107,9 @@ pub enum ArtifactState {
},
/// A task to prepare this artifact is scheduled.
Preparing,
/// The code couldn't be compiled due to an error. Such artifacts
/// never reach the executor and stay in the host's memory.
FailedToProcess(PrepareError),
}
/// A container of all known artifact ids and their states.
......
......@@ -14,6 +14,20 @@
// You should have received a copy of the GNU General Public License
// along with Polkadot. If not, see <http://www.gnu.org/licenses/>.
use parity_scale_codec::{Decode, Encode};
/// An error that occurred during the prepare part of the PVF pipeline.
#[derive(Debug, Clone, Encode, Decode)]
pub enum PrepareError {
/// During the prevalidation stage of preparation an issue was found with the PVF.
Prevalidation(String),
/// Compilation failed for the given PVF.
Preparation(String),
/// This state indicates that the process assigned to prepare the artifact wasn't responsible
/// or were killed. This state is reported by the validation host (not by the worker).
DidNotMakeIt,
}
/// A error raised during validation of the candidate.
#[derive(Debug, Clone)]
pub enum ValidationError {
......@@ -54,3 +68,14 @@ pub enum InvalidCandidate {
/// PVF execution (compilation is not included) took more time than was allotted.
HardTimeout,
}
impl From<PrepareError> for ValidationError {
fn from(error: PrepareError) -> Self {
let error_str = match error {
PrepareError::Prevalidation(err) => err,
PrepareError::Preparation(err) => err,
PrepareError::DidNotMakeIt => "preparation timeout".to_owned(),
};
ValidationError::InvalidCandidate(InvalidCandidate::WorkerReportedError(error_str))
}
}
......@@ -15,7 +15,7 @@
// along with Polkadot. If not, see <http://www.gnu.org/licenses/>.
use crate::{
artifacts::{Artifact, ArtifactPathId},
artifacts::{ArtifactPathId, CompiledArtifact},
executor_intf::TaskExecutor,
worker_common::{
bytes_to_path, framed_recv, framed_send, path_to_bytes, spawn_with_program_path,
......@@ -49,8 +49,8 @@ pub enum Outcome {
/// PVF execution completed successfully and the result is returned. The worker is ready for
/// another job.
Ok { result_descriptor: ValidationResult, duration_ms: u64, idle_worker: IdleWorker },
/// The candidate validation failed. It may be for example because the preparation process
/// produced an error or the wasm execution triggered a trap.
/// The candidate validation failed. It may be for example because the wasm execution triggered a trap.
/// Errors related to the preparation process are not expected to be encountered by the execution workers.
InvalidCandidate { err: String, idle_worker: IdleWorker },
/// An internal error happened during the validation. Such an error is most likely related to
/// some transient glitch.
......@@ -216,18 +216,12 @@ async fn validate_using_artifact(
Ok(b) => b,
};
let artifact = match Artifact::deserialize(&artifact_bytes) {
let artifact = match CompiledArtifact::decode(&mut artifact_bytes.as_slice()) {
Err(e) => return Response::InternalError(format!("artifact deserialization: {:?}", e)),
Ok(a) => a,
};
let compiled_artifact = match &artifact {
Artifact::PrevalidationErr(msg) => return Response::format_invalid("prevalidation", msg),
Artifact::PreparationErr(msg) => return Response::format_invalid("preparation", msg),
Artifact::DidntMakeIt => return Response::format_invalid("preparation timeout", ""),
Artifact::Compiled { compiled_artifact } => compiled_artifact,
};
let compiled_artifact = artifact.as_ref();
let validation_started_at = Instant::now();
let descriptor_bytes = match unsafe {
......
......@@ -344,8 +344,7 @@ async fn run(
.await);
},
from_prepare_queue = from_prepare_queue_rx.next() => {
let prepare::FromQueue::Prepared(artifact_id)
= break_if_fatal!(from_prepare_queue.ok_or(Fatal));
let from_queue = break_if_fatal!(from_prepare_queue.ok_or(Fatal));
// Note that preparation always succeeds.
//
......@@ -361,7 +360,7 @@ async fn run(
&mut artifacts,
&mut to_execute_queue_tx,
&mut awaiting_prepare,
artifact_id,
from_queue,
).await);
},
}
......@@ -439,6 +438,9 @@ async fn handle_execute_pvf(
awaiting_prepare.add(artifact_id, execution_timeout, params, result_tx);
},
ArtifactState::FailedToProcess(error) => {
let _ = result_tx.send(Err(ValidationError::from(error.clone())));
},
}
} else {
// Artifact is unknown: register it and enqueue a job with the corresponding priority and
......@@ -470,6 +472,7 @@ async fn handle_heads_up(
// Already preparing. We don't need to send a priority amend either because
// it can't get any lower than the background.
},
ArtifactState::FailedToProcess(_) => {},
}
} else {
// The artifact is unknown: register it and put a background job into the prepare queue.
......@@ -491,8 +494,10 @@ async fn handle_prepare_done(
artifacts: &mut Artifacts,
execute_queue: &mut mpsc::Sender<execute::ToQueue>,
awaiting_prepare: &mut AwaitingPrepare,
artifact_id: ArtifactId,
from_queue: prepare::FromQueue,
) -> Result<(), Fatal> {
let prepare::FromQueue { artifact_id, result } = from_queue;
// Make some sanity checks and extract the current state.
let state = match artifacts.artifact_state_mut(&artifact_id) {
None => {
......@@ -513,6 +518,12 @@ async fn handle_prepare_done(
never!("the artifact is already prepared: {:?}", artifact_id);
return Ok(())
},
Some(ArtifactState::FailedToProcess(_)) => {
// The reasoning is similar to the above, the artifact cannot be
// processed at this point.
never!("the artifact is already processed unsuccessfully: {:?}", artifact_id);
return Ok(())
},
Some(state @ ArtifactState::Preparing) => state,
};
......@@ -526,6 +537,12 @@ async fn handle_prepare_done(
continue
}
// Don't send failed artifacts to the execution's queue.
if let Err(ref error) = result {
let _ = result_tx.send(Err(ValidationError::from(error.clone())));
continue
}
send_execute(
execute_queue,
execute::ToQueue::Enqueue {
......@@ -538,8 +555,10 @@ async fn handle_prepare_done(
.await?;
}
// Now consider the artifact prepared.
*state = ArtifactState::Prepared { last_time_needed: SystemTime::now() };
*state = match result {
Ok(()) => ArtifactState::Prepared { last_time_needed: SystemTime::now() },
Err(error) => ArtifactState::FailedToProcess(error.clone()),
};
Ok(())
}
......@@ -937,7 +956,7 @@ mod tests {
);
test.from_prepare_queue_tx
.send(prepare::FromQueue::Prepared(artifact_id(1)))
.send(prepare::FromQueue { artifact_id: artifact_id(1), result: Ok(()) })
.await
.unwrap();
let result_tx_pvf_1_1 = assert_matches!(
......@@ -950,7 +969,7 @@ mod tests {
);
test.from_prepare_queue_tx
.send(prepare::FromQueue::Prepared(artifact_id(2)))
.send(prepare::FromQueue { artifact_id: artifact_id(2), result: Ok(()) })
.await
.unwrap();
let result_tx_pvf_2 = assert_matches!(
......@@ -1005,7 +1024,7 @@ mod tests {
);
test.from_prepare_queue_tx
.send(prepare::FromQueue::Prepared(artifact_id(1)))
.send(prepare::FromQueue { artifact_id: artifact_id(1), result: Ok(()) })
.await
.unwrap();
......
......@@ -16,6 +16,7 @@
use super::worker::{self, Outcome};
use crate::{
error::PrepareError,
metrics::Metrics,
worker_common::{IdleWorker, WorkerHandle},
LOG_TARGET,
......@@ -78,9 +79,16 @@ pub enum FromPool {
/// The given worker was just spawned and is ready to be used.
Spawned(Worker),
/// The given worker either succeeded or failed the given job. Under any circumstances the
/// artifact file has been written. The `bool` says whether the worker ripped.
Concluded(Worker, bool),
/// The given worker either succeeded or failed the given job.
Concluded {
/// A key for retrieving the worker data from the pool.
worker: Worker,
/// Indicates whether the worker process was killed.
rip: bool,
/// [`Ok`] indicates that compiled artifact is successfully stored on disk.
/// Otherwise, an [error](PrepareError) is supplied.
result: Result<(), PrepareError>,
},
/// The given worker ceased to exist.
Rip(Worker),
......@@ -295,7 +303,7 @@ fn handle_mux(
},
PoolEvent::StartWork(worker, outcome) => {
match outcome {
Outcome::Concluded(idle) => {
Outcome::Concluded { worker: idle, result } => {
let data = match spawned.get_mut(worker) {
None => {
// Perhaps the worker was killed meanwhile and the result is no longer
......@@ -310,7 +318,7 @@ fn handle_mux(
let old = data.idle.replace(idle);
assert_matches!(old, None, "attempt to overwrite an idle worker");
reply(from_pool, FromPool::Concluded(worker, false))?;
reply(from_pool, FromPool::Concluded { worker, rip: false, result })?;
Ok(())
},
......@@ -321,9 +329,16 @@ fn handle_mux(
Ok(())
},
Outcome::DidntMakeIt => {
Outcome::DidNotMakeIt => {
if attempt_retire(metrics, spawned, worker) {
reply(from_pool, FromPool::Concluded(worker, true))?;
reply(
from_pool,
FromPool::Concluded {
worker,
rip: true,
result: Err(PrepareError::DidNotMakeIt),
},
)?;
}
Ok(())
......
......@@ -17,7 +17,9 @@
//! A queue that handles requests for PVF preparation.
use super::pool::{self, Worker};
use crate::{artifacts::ArtifactId, metrics::Metrics, Priority, Pvf, LOG_TARGET};
use crate::{
artifacts::ArtifactId, error::PrepareError, metrics::Metrics, Priority, Pvf, LOG_TARGET,
};
use always_assert::{always, never};
use async_std::path::PathBuf;
use futures::{channel::mpsc, stream::StreamExt as _, Future, SinkExt};
......@@ -29,7 +31,7 @@ pub enum ToQueue {
/// This schedules preparation of the given PVF.
///
/// Note that it is incorrect to enqueue the same PVF again without first receiving the
/// [`FromQueue::Prepared`] response. In case there is a need to bump the priority, use
/// [`FromQueue`] response. In case there is a need to bump the priority, use
/// [`ToQueue::Amend`].
Enqueue { priority: Priority, pvf: Pvf },
/// Amends the priority for the given [`ArtifactId`] if it is running. If it's not, then it's noop.
......@@ -37,9 +39,13 @@ pub enum ToQueue {
}
/// A response from queue.
#[derive(Debug, PartialEq, Eq)]
pub enum FromQueue {
Prepared(ArtifactId),
#[derive(Debug)]
pub struct FromQueue {
/// Identifier of an artifact.
pub(crate) artifact_id: ArtifactId,
/// Outcome of the PVF processing. [`Ok`] indicates that compiled artifact
/// is successfully stored on disk. Otherwise, an [error](PrepareError) is supplied.
pub(crate) result: Result<(), PrepareError>,
}
#[derive(Default)]
......@@ -299,7 +305,8 @@ async fn handle_from_pool(queue: &mut Queue, from_pool: pool::FromPool) -> Resul
use pool::FromPool::*;
match from_pool {
Spawned(worker) => handle_worker_spawned(queue, worker).await?,
Concluded(worker, rip) => handle_worker_concluded(queue, worker, rip).await?,
Concluded { worker, rip, result } =>
handle_worker_concluded(queue, worker, rip, result).await?,
Rip(worker) => handle_worker_rip(queue, worker).await?,
}
Ok(())
......@@ -320,6 +327,7 @@ async fn handle_worker_concluded(
queue: &mut Queue,
worker: Worker,
rip: bool,
result: Result<(), PrepareError>,
) -> Result<(), Fatal> {
queue.metrics.prepare_concluded();
......@@ -377,7 +385,7 @@ async fn handle_worker_concluded(
"prepare worker concluded",
);
reply(&mut queue.from_queue_tx, FromQueue::Prepared(artifact_id))?;
reply(&mut queue.from_queue_tx, FromQueue { artifact_id, result })?;
// Figure out what to do with the worker.
if rip {
......@@ -641,12 +649,9 @@ mod tests {
let w = test.workers.insert(());
test.send_from_pool(pool::FromPool::Spawned(w));
test.send_from_pool(pool::FromPool::Concluded(w, false));
test.send_from_pool(pool::FromPool::Concluded { worker: w, rip: false, result: Ok(()) });
assert_eq!(
test.poll_and_recv_from_queue().await,
FromQueue::Prepared(pvf(1).as_artifact_id())
);
assert_eq!(test.poll_and_recv_from_queue().await.artifact_id, pvf(1).as_artifact_id());
}
#[async_std::test]
......@@ -671,7 +676,7 @@ mod tests {
assert_matches!(test.poll_and_recv_to_pool().await, pool::ToPool::StartWork { .. });
assert_matches!(test.poll_and_recv_to_pool().await, pool::ToPool::StartWork { .. });
test.send_from_pool(pool::FromPool::Concluded(w1, false));
test.send_from_pool(pool::FromPool::Concluded { worker: w1, rip: false, result: Ok(()) });
assert_matches!(test.poll_and_recv_to_pool().await, pool::ToPool::StartWork { .. });
......@@ -704,7 +709,7 @@ mod tests {
// That's a bit silly in this context, but in production there will be an entire pool up
// to the `soft_capacity` of workers and it doesn't matter which one to cull. Either way,
// we just check that edge case of an edge case works.
test.send_from_pool(pool::FromPool::Concluded(w1, false));
test.send_from_pool(pool::FromPool::Concluded { worker: w1, rip: false, result: Ok(()) });
assert_eq!(test.poll_and_recv_to_pool().await, pool::ToPool::Kill(w1));
}
......@@ -749,15 +754,12 @@ mod tests {
assert_matches!(test.poll_and_recv_to_pool().await, pool::ToPool::StartWork { .. });
// Conclude worker 1 and rip it.
test.send_from_pool(pool::FromPool::Concluded(w1, true));
test.send_from_pool(pool::FromPool::Concluded { worker: w1, rip: true, result: Ok(()) });
// Since there is still work, the queue requested one extra worker to spawn to handle the
// remaining enqueued work items.
assert_eq!(test.poll_and_recv_to_pool().await, pool::ToPool::Spawn);
assert_eq!(
test.poll_and_recv_from_queue().await,
FromQueue::Prepared(pvf(1).as_artifact_id())
);
assert_eq!(test.poll_and_recv_from_queue().await.artifact_id, pvf(1).as_artifact_id());
}
#[async_std::test]
......@@ -773,7 +775,11 @@ mod tests {
assert_matches!(test.poll_and_recv_to_pool().await, pool::ToPool::StartWork { .. });
test.send_from_pool(pool::FromPool::Concluded(w1, true));
test.send_from_pool(pool::FromPool::Concluded {
worker: w1,
rip: true,
result: Err(PrepareError::DidNotMakeIt),
});
test.poll_ensure_to_pool_is_empty().await;
}
......
......@@ -15,7 +15,8 @@
// along with Polkadot. If not, see <http://www.gnu.org/licenses/>.
use crate::{
artifacts::Artifact,
artifacts::CompiledArtifact,
error::PrepareError,
worker_common::{
bytes_to_path, framed_recv, framed_send, path_to_bytes, spawn_with_program_path,
tmpfile_in, worker_event_loop, IdleWorker, SpawnErr, WorkerHandle,
......@@ -29,6 +30,8 @@ use async_std::{
};
use futures::FutureExt as _;
use futures_timer::Delay;
use parity_scale_codec::{Decode, Encode};
use sp_core::hexdisplay::HexDisplay;
use std::{sync::Arc, time::Duration};
const NICENESS_BACKGROUND: i32 = 10;
......@@ -48,7 +51,7 @@ pub async fn spawn(
pub enum Outcome {
/// The worker has finished the work assigned to it.
Concluded(IdleWorker),
Concluded { worker: IdleWorker, result: Result<(), PrepareError> },
/// The host tried to reach the worker but failed. This is most likely because the worked was
/// killed by the system.
Unreachable,
......@@ -59,7 +62,7 @@ pub enum Outcome {
/// the artifact).
///
/// This doesn't return an idle worker instance, thus this worker is no longer usable.
DidntMakeIt,
DidNotMakeIt,
}
/// Given the idle token of a worker and parameters of work, communicates with the worker and
......@@ -99,13 +102,11 @@ pub async fn start_work(
// Wait for the result from the worker, keeping in mind that there may be a timeout, the
// worker may get killed, or something along these lines.
//
// In that case we should handle these gracefully by writing the artifact file by ourselves.
// We may potentially overwrite the artifact in rare cases where the worker didn't make
// it to report back the result.
// In that case we should propagate the error to the pool.
#[derive(Debug)]
enum Selected {
Done,
Done(Result<(), PrepareError>),
IoErr,
Deadline,
}
......@@ -113,41 +114,48 @@ pub async fn start_work(
let selected = futures::select! {
res = framed_recv(&mut stream).fuse() => {
match res {
Ok(x) if x == &[1u8] => {
tracing::debug!(
target: LOG_TARGET,
worker_pid = %pid,
"promoting WIP artifact {} to {}",
tmp_file.display(),
artifact_path.display(),
);
async_std::fs::rename(&tmp_file, &artifact_path)
.await
.map(|_| Selected::Done)
.unwrap_or_else(|err| {
tracing::warn!(
Ok(response_bytes) => {
// By convention we expect encoded `Result<(), PrepareError>`.
if let Ok(result) =
<Result<(), PrepareError>>::decode(&mut response_bytes.clone().as_slice())
{
if result.is_ok() {
tracing::debug!(
target: LOG_TARGET,
worker_pid = %pid,
"failed to rename the artifact from {} to {}: {:?}",
"promoting WIP artifact {} to {}",
tmp_file.display(),
artifact_path.display(),
err,
);
Selected::IoErr
})
}
Ok(response_bytes) => {
use sp_core::hexdisplay::HexDisplay;
let bound_bytes =
&response_bytes[..response_bytes.len().min(4)];
tracing::warn!(
target: LOG_TARGET,
worker_pid = %pid,
"received unexpected response from the prepare worker: {}",
HexDisplay::from(&bound_bytes),
);
Selected::IoErr
async_std::fs::rename(&tmp_file, &artifact_path)
.await
.map(|_| Selected::Done(result))
.unwrap_or_else(|err| {
tracing::warn!(
target: LOG_TARGET,
worker_pid = %pid,
"failed to rename the artifact from {} to {}: {:?}",
tmp_file.display(),
artifact_path.display(),
err,
);
Selected::IoErr
})
} else {
Selected::Done(result)
}
} else {
// We received invalid bytes from the worker.
let bound_bytes = &response_bytes[..response_bytes.len().min(4)];
tracing::warn!(
target: LOG_TARGET,
worker_pid = %pid,
"received unexpected response from the prepare worker: {}",
HexDisplay::from(&bound_bytes),
);
Selected::IoErr
}
},
Err(err) => {
tracing::warn!(
......@@ -164,24 +172,11 @@ pub async fn start_work(
};
match selected {
Selected::Done => {
Selected::Done(result) => {
renice(pid, NICENESS_FOREGROUND);
Outcome::Concluded(IdleWorker { stream, pid })
},
Selected::IoErr | Selected::Deadline => {
let bytes = Artifact::DidntMakeIt.serialize();
// best effort: there is nothing we can do here if the write fails.
if let Err(err) = async_std::fs::write(&artifact_path, &bytes).await {
tracing::warn!(
target: LOG_TARGET,
worker_pid = %pid,
"preparation didn't make it, because of `{:?}`: {:?}",
selected,
err,
);
}
Outcome::DidntMakeIt
Outcome::Concluded { worker: IdleWorker { stream, pid }, result }
},
Selected::IoErr | Selected::Deadline => Outcome::DidNotMakeIt,
}
})
.await
......@@ -205,7 +200,7 @@ where
"failed to create a temp file for the artifact: {:?}",
err,
);
return Outcome::DidntMakeIt
return Outcome::DidNotMakeIt
},
};
......@@ -288,31 +283,47 @@ pub fn worker_entrypoint(socket_path: &str) {
worker_pid = %std::process::id(),
"worker: preparing artifact",
);
let artifact_bytes = prepare_artifact(&code).serialize();
// Write the serialized artifact into into a temp file.
tracing::debug!(
target: LOG_TARGET,
worker_pid = %std::process::id(),
"worker: writing artifact to {}",
dest.display(),
);
async_std::fs::write(&dest, &artifact_bytes).await?;<