| // Copyright 2015 The Bazel Authors. All rights reserved. |
| // |
| // Licensed 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 com.google.devtools.build.lib.worker; |
| |
| import com.google.common.base.Throwables; |
| import com.google.common.collect.ImmutableMap; |
| import com.google.common.collect.ImmutableSet; |
| import java.io.IOException; |
| import java.util.Map; |
| import java.util.concurrent.atomic.AtomicInteger; |
| import javax.annotation.concurrent.ThreadSafe; |
| import org.apache.commons.pool2.impl.GenericKeyedObjectPool; |
| |
| /** |
| * A worker pool that spawns multiple workers and delegates work to them. Allows separate |
| * configuration for singleplex and multiplex workers. While the configuration is per mnemonic, the |
| * actual pools need to be per WorkerKey, as different WorkerKeys may imply different process |
| * startup options. |
| * |
| * <p>This is useful when the worker cannot handle multiple parallel requests on its own and we need |
| * to pre-fork a couple of them instead. Multiplex workers <em>can</em> handle multiple parallel |
| * requests, but do so through WorkerProxy instances. |
| */ |
| @ThreadSafe |
| final class WorkerPool { |
| /** Unless otherwise specified, the max number of workers per WorkerKey. */ |
| private static final int DEFAULT_MAX_WORKERS = 4; |
| /** Unless otherwise specified, the max number of multiplex workers per WorkerKey. */ |
| private static final int DEFAULT_MAX_MULTIPLEX_WORKERS = 8; |
| /** |
| * How many high-priority workers are currently borrowed. If greater than one, low-priority |
| * workers cannot be borrowed until the high-priority ones are done. |
| */ |
| private final AtomicInteger highPriorityWorkersInUse = new AtomicInteger(0); |
| /** Which mnemonics create high-priority workers. */ |
| private final ImmutableSet<String> highPriorityWorkerMnemonics; |
| /** Map of singleplex worker pools, one per mnemonic. */ |
| private final ImmutableMap<String, SimpleWorkerPool> workerPools; |
| /** Map of multiplex worker pools, one per mnemonic. */ |
| private final ImmutableMap<String, SimpleWorkerPool> multiplexPools; |
| |
| /** |
| * @param factory worker factory |
| * @param config pool configuration; max number of workers per WorkerKey for each mnemonic; the |
| * empty string key specifies the default maximum |
| * @param multiplexConfig like {@code config}, but for multiplex workers |
| * @param highPriorityWorkers mnemonics of high priority workers |
| */ |
| public WorkerPool( |
| WorkerFactory factory, |
| Map<String, Integer> config, |
| Map<String, Integer> multiplexConfig, |
| Iterable<String> highPriorityWorkers) { |
| highPriorityWorkerMnemonics = ImmutableSet.copyOf(highPriorityWorkers); |
| workerPools = createWorkerPools(factory, config, DEFAULT_MAX_WORKERS); |
| multiplexPools = createWorkerPools(factory, multiplexConfig, DEFAULT_MAX_MULTIPLEX_WORKERS); |
| } |
| |
| private static ImmutableMap<String, SimpleWorkerPool> createWorkerPools( |
| WorkerFactory factory, Map<String, Integer> config, int defaultMaxWorkers) { |
| ImmutableMap.Builder<String, SimpleWorkerPool> workerPoolsBuilder = ImmutableMap.builder(); |
| config.forEach( |
| (key, value) -> |
| workerPoolsBuilder.put(key, new SimpleWorkerPool(factory, makeConfig(value)))); |
| if (!config.containsKey("")) { |
| workerPoolsBuilder.put("", new SimpleWorkerPool(factory, makeConfig(defaultMaxWorkers))); |
| } |
| return workerPoolsBuilder.build(); |
| } |
| |
| private static WorkerPoolConfig makeConfig(int max) { |
| WorkerPoolConfig config = new WorkerPoolConfig(); |
| |
| // It's better to re-use a worker as often as possible and keep it hot, in order to profit |
| // from JIT optimizations as much as possible. |
| config.setLifo(true); |
| |
| // Keep a fixed number of workers running per key. |
| config.setMaxIdlePerKey(max); |
| config.setMaxTotalPerKey(max); |
| config.setMinIdlePerKey(max); |
| |
| // Don't limit the total number of worker processes, as otherwise the pool might be full of |
| // workers for one WorkerKey and can't accommodate a worker for another WorkerKey. |
| config.setMaxTotal(-1); |
| |
| // Wait for a worker to become ready when a thread needs one. |
| config.setBlockWhenExhausted(true); |
| |
| // Always test the liveliness of worker processes. |
| config.setTestOnBorrow(true); |
| config.setTestOnCreate(true); |
| config.setTestOnReturn(true); |
| |
| // No eviction of idle workers. |
| config.setTimeBetweenEvictionRunsMillis(-1); |
| |
| return config; |
| } |
| |
| private SimpleWorkerPool getPool(WorkerKey key) { |
| if (key.getProxied()) { |
| return multiplexPools.getOrDefault(key.getMnemonic(), multiplexPools.get("")); |
| } else { |
| return workerPools.getOrDefault(key.getMnemonic(), workerPools.get("")); |
| } |
| } |
| |
| /** |
| * Gets a worker. May block indefinitely if too many high-priority workers are in use and the |
| * requested worker is not high priority. |
| * |
| * @param key worker key |
| * @return a worker |
| */ |
| public Worker borrowObject(WorkerKey key) throws IOException, InterruptedException { |
| Worker result; |
| try { |
| result = getPool(key).borrowObject(key); |
| } catch (Throwable t) { |
| Throwables.propagateIfPossible(t, IOException.class, InterruptedException.class); |
| throw new RuntimeException("unexpected", t); |
| } |
| |
| if (highPriorityWorkerMnemonics.contains(key.getMnemonic())) { |
| highPriorityWorkersInUse.incrementAndGet(); |
| } else { |
| try { |
| waitForHighPriorityWorkersToFinish(); |
| } catch (InterruptedException e) { |
| returnObject(key, result); |
| throw e; |
| } |
| } |
| |
| return result; |
| } |
| |
| public void returnObject(WorkerKey key, Worker obj) { |
| if (highPriorityWorkerMnemonics.contains(key.getMnemonic())) { |
| decrementHighPriorityWorkerCount(); |
| } |
| getPool(key).returnObject(key, obj); |
| } |
| |
| public void invalidateObject(WorkerKey key, Worker obj) throws IOException, InterruptedException { |
| if (highPriorityWorkerMnemonics.contains(key.getMnemonic())) { |
| decrementHighPriorityWorkerCount(); |
| } |
| try { |
| getPool(key).invalidateObject(key, obj); |
| } catch (Throwable t) { |
| Throwables.propagateIfPossible(t, IOException.class, InterruptedException.class); |
| throw new RuntimeException("unexpected", t); |
| } |
| } |
| |
| // Decrements the high-priority workers counts and pings waiting threads if appropriate. |
| private void decrementHighPriorityWorkerCount() { |
| if (highPriorityWorkersInUse.decrementAndGet() <= 1) { |
| synchronized (highPriorityWorkersInUse) { |
| highPriorityWorkersInUse.notifyAll(); |
| } |
| } |
| } |
| |
| // Returns once less than two high-priority workers are running. |
| private void waitForHighPriorityWorkersToFinish() throws InterruptedException { |
| // Fast path for the case where the high-priority workers feature is not in use. |
| if (highPriorityWorkerMnemonics.isEmpty()) { |
| return; |
| } |
| |
| while (highPriorityWorkersInUse.get() > 1) { |
| synchronized (highPriorityWorkersInUse) { |
| highPriorityWorkersInUse.wait(); |
| } |
| } |
| } |
| |
| public void close() { |
| workerPools.values().forEach(GenericKeyedObjectPool::close); |
| multiplexPools.values().forEach(GenericKeyedObjectPool::close); |
| } |
| |
| /** Stops any ongoing work in the worker pools. This may entail killing the worker processes. */ |
| public void stopWork() { |
| workerPools |
| .values() |
| .forEach( |
| pool -> { |
| if (pool.getNumActive() > 0) { |
| pool.clear(); |
| } |
| }); |
| multiplexPools |
| .values() |
| .forEach( |
| pool -> { |
| if (pool.getNumActive() > 0) { |
| pool.clear(); |
| } |
| }); |
| } |
| } |