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Posted to commits@pinot.apache.org by GitBox <gi...@apache.org> on 2022/11/07 23:16:55 UTC
[GitHub] [pinot] agavra commented on a diff in pull request #9753: [multistage] implement naive round robin operator chain scheduling
agavra commented on code in PR #9753:
URL: https://github.com/apache/pinot/pull/9753#discussion_r1015990164
##########
pinot-query-runtime/src/main/java/org/apache/pinot/query/runtime/executor/OpChainSchedulerService.java:
##########
@@ -0,0 +1,147 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.pinot.query.runtime.executor;
+
+import com.google.common.util.concurrent.AbstractExecutionThreadService;
+import com.google.common.util.concurrent.Monitor;
+import java.util.concurrent.ExecutorService;
+import org.apache.pinot.common.request.context.ThreadTimer;
+import org.apache.pinot.core.util.trace.TraceRunnable;
+import org.apache.pinot.query.mailbox.MailboxIdentifier;
+import org.apache.pinot.query.runtime.blocks.TransferableBlock;
+import org.apache.pinot.query.runtime.operator.OpChain;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+
+/**
+ * This class provides the implementation for scheduling multistage queries on a single node based
+ * on the {@link OpChainScheduler} logic that is passed in. Multistage queries support partial execution
+ * and will return a NOOP metadata block as a "yield" signal, indicating that the next operator
+ * chain ({@link OpChainScheduler#next()} will be requested.
+ *
+ * <p>Note that a yielded operator chain will be re-registered with the underlying scheduler.
+ */
+@SuppressWarnings("UnstableApiUsage")
+public class OpChainSchedulerService extends AbstractExecutionThreadService {
+
+ private static final Logger LOGGER = LoggerFactory.getLogger(OpChainSchedulerService.class);
+
+ private final OpChainScheduler _scheduler;
+ private final ExecutorService _workerPool;
+
+ // anything that is guarded by this monitor should be non-blocking
+ private final Monitor _monitor = new Monitor();
+ protected final Monitor.Guard _hasNextOrClosing = new Monitor.Guard(_monitor) {
+ @Override
+ public boolean isSatisfied() {
+ return _scheduler.hasNext() || !isRunning();
+ }
+ };
+
+ public OpChainSchedulerService(OpChainScheduler scheduler, ExecutorService workerPool) {
+ _scheduler = scheduler;
+ _workerPool = workerPool;
+ }
+
+ @Override
+ protected void triggerShutdown() {
+ // this wil just notify all waiters that the scheduler is shutting down
+ _monitor.enter();
+ _monitor.leave();
+ }
+
+ @Override
+ protected void run()
+ throws Exception {
+ while (isRunning()) {
+ _monitor.enterWhen(_hasNextOrClosing);
+ try {
+ if (!isRunning()) {
+ return;
+ }
+
+ OpChain operatorChain = _scheduler.next();
+ _workerPool.submit(new TraceRunnable() {
+ @Override
+ public void runJob() {
+ try {
+ ThreadTimer timer = operatorChain.getAndStartTimer();
+
+ // so long as there's work to be done, keep getting the next block
+ // when the operator chain returns a NOOP block, then yield the execution
+ // of this to another worker
+ TransferableBlock result = operatorChain.getRoot().nextBlock();
+ while (!result.isNoOpBlock() && !result.isEndOfStreamBlock()) {
+ LOGGER.debug("Got block with {} rows.", result.getNumRows());
+ result = operatorChain.getRoot().nextBlock();
+ }
+
+ if (!result.isEndOfStreamBlock()) {
+ // not complete, needs to re-register for scheduling
+ register(operatorChain);
+ } else {
+ LOGGER.info("Execution time: " + timer.getThreadTimeNs());
Review Comment:
for more complex scheduling algorithms, we will add a callback here to `complete` or `unregister` an operator chain. that requires a unique way to identify operator chains which adds a bit more code so I avoided it for this PR
##########
pinot-query-runtime/src/main/java/org/apache/pinot/query/runtime/executor/OpChainSchedulerService.java:
##########
@@ -0,0 +1,147 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.pinot.query.runtime.executor;
+
+import com.google.common.util.concurrent.AbstractExecutionThreadService;
+import com.google.common.util.concurrent.Monitor;
+import java.util.concurrent.ExecutorService;
+import org.apache.pinot.common.request.context.ThreadTimer;
+import org.apache.pinot.core.util.trace.TraceRunnable;
+import org.apache.pinot.query.mailbox.MailboxIdentifier;
+import org.apache.pinot.query.runtime.blocks.TransferableBlock;
+import org.apache.pinot.query.runtime.operator.OpChain;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+
+/**
+ * This class provides the implementation for scheduling multistage queries on a single node based
+ * on the {@link OpChainScheduler} logic that is passed in. Multistage queries support partial execution
+ * and will return a NOOP metadata block as a "yield" signal, indicating that the next operator
+ * chain ({@link OpChainScheduler#next()} will be requested.
+ *
+ * <p>Note that a yielded operator chain will be re-registered with the underlying scheduler.
+ */
+@SuppressWarnings("UnstableApiUsage")
+public class OpChainSchedulerService extends AbstractExecutionThreadService {
+
+ private static final Logger LOGGER = LoggerFactory.getLogger(OpChainSchedulerService.class);
+
+ private final OpChainScheduler _scheduler;
+ private final ExecutorService _workerPool;
+
+ // anything that is guarded by this monitor should be non-blocking
+ private final Monitor _monitor = new Monitor();
+ protected final Monitor.Guard _hasNextOrClosing = new Monitor.Guard(_monitor) {
+ @Override
+ public boolean isSatisfied() {
+ return _scheduler.hasNext() || !isRunning();
+ }
+ };
+
+ public OpChainSchedulerService(OpChainScheduler scheduler, ExecutorService workerPool) {
+ _scheduler = scheduler;
+ _workerPool = workerPool;
+ }
+
+ @Override
+ protected void triggerShutdown() {
+ // this wil just notify all waiters that the scheduler is shutting down
+ _monitor.enter();
+ _monitor.leave();
+ }
+
+ @Override
+ protected void run()
+ throws Exception {
+ while (isRunning()) {
+ _monitor.enterWhen(_hasNextOrClosing);
+ try {
+ if (!isRunning()) {
+ return;
+ }
+
+ OpChain operatorChain = _scheduler.next();
+ _workerPool.submit(new TraceRunnable() {
+ @Override
+ public void runJob() {
+ try {
+ ThreadTimer timer = operatorChain.getAndStartTimer();
+
+ // so long as there's work to be done, keep getting the next block
+ // when the operator chain returns a NOOP block, then yield the execution
+ // of this to another worker
+ TransferableBlock result = operatorChain.getRoot().nextBlock();
+ while (!result.isNoOpBlock() && !result.isEndOfStreamBlock()) {
+ LOGGER.debug("Got block with {} rows.", result.getNumRows());
+ result = operatorChain.getRoot().nextBlock();
+ }
+
+ if (!result.isEndOfStreamBlock()) {
+ // not complete, needs to re-register for scheduling
+ register(operatorChain);
+ } else {
+ LOGGER.info("Execution time: " + timer.getThreadTimeNs());
+ }
+ } catch (Exception e) {
+ LOGGER.error("Failed to execute query!", e);
+ }
+ }
+ });
+ } finally {
+ _monitor.leave();
+ }
+ }
+ }
+
+ /**
+ * Register a new operator chain with the scheduler.
+ *
+ * @param operatorChain the chain to register
+ */
+ public final void register(OpChain operatorChain) {
+ _monitor.enter();
+ try {
+ _scheduler.register(operatorChain);
+ } finally {
+ _monitor.leave();
+ }
+ }
+
+ /**
+ * This method should be called whenever data is available in a given mailbox.
+ * Implementations of this method should be idempotent, it may be called in the
+ * scenario that no mail is available.
+ *
+ * @param mailbox the identifier of the mailbox that now has data
+ */
+ public final void onDataAvailable(MailboxIdentifier mailbox) {
+ _monitor.enter();
+ try {
+ _scheduler.onDataAvailable(mailbox);
+ } finally {
+ _monitor.leave();
+ }
+ }
+
+ // TODO: remove this method after we pipe down the proper executor pool to the v1 engine
Review Comment:
this is a bit unfortunate, but it's how the existing code works and refactoring it would be out of scope for this PR. While it's not particularly efficient, it also isn't dangerous - V1 queries are non-blocking, so using the same worker pool for executing V1 queries (that are issued as part of V2) and V2 intermediate queries does not threaten liveness.
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