nsivabalan commented on code in PR #18984: URL: https://github.com/apache/hudi/pull/18984#discussion_r3647182976
########## hudi-sync/hudi-hive-sync/src/main/java/org/apache/hudi/hive/util/HiveDriverPool.java: ########## @@ -0,0 +1,334 @@ +/* + * 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.hudi.hive.util; + +import org.apache.hudi.exception.HoodieException; +import org.apache.hudi.hive.HiveSyncConfig; +import org.apache.hudi.hive.HoodieHiveSyncException; + +import org.apache.hadoop.hive.conf.HiveConf; +import org.apache.hadoop.hive.ql.Driver; +import org.apache.hadoop.hive.ql.session.SessionState; +import org.apache.hadoop.security.UserGroupInformation; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.util.ArrayList; +import java.util.List; +import java.util.concurrent.CancellationException; +import java.util.concurrent.ExecutionException; +import java.util.concurrent.ExecutorService; +import java.util.concurrent.Executors; +import java.util.concurrent.Future; +import java.util.concurrent.ThreadFactory; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicInteger; + +import static org.apache.hudi.sync.common.HoodieSyncConfig.META_SYNC_DATABASE_NAME; + +/** + * Pool of Hive {@link Driver} + {@link SessionState} pairs for parallel HiveQL DDL. + * + * <p>Hive's {@code SessionState.start(state)} binds state to the calling thread's + * thread-local, and {@code Driver} reads from that thread-local during {@code run()}. + * A Driver constructed on one thread cannot be safely used from another. This pool + * solves that by giving each slot its own dedicated worker thread (a single-thread + * executor) — the Driver and SessionState are built on that thread by a bootstrap + * task, and all subsequent SQL for that slot runs on the same thread. + * + * <p><b>Usage contract:</b> use this pool only for partition-row DDL statements that + * are independent of each other and freely shuffleable across workers. Table-level + * statements (createTable, schema evolution, USE database) must continue to run on + * the session {@code Driver} held by {@code HiveQueryDDLExecutor} on the sync driver + * thread. The pool is gated behind {@code hoodie.datasource.hive_sync.batching.enabled} + * and is constructed only for HiveQL sync mode. + */ +public class HiveDriverPool implements AutoCloseable { + + private static final Logger LOG = LoggerFactory.getLogger(HiveDriverPool.class); + + // Per-worker Driver construction has to be fast in practice (a few hundred ms + // for the SessionState + Driver init). A 60s ceiling per worker leaves plenty of + // headroom for a slow JVM warm-up but bounds the failure mode if the metastore + // is unreachable or Hive hangs during init. + private static final long BOOTSTRAP_TIMEOUT_SECONDS = 60; + + private final List<Worker> workers; + private final int size; + private volatile boolean closed; + + public HiveDriverPool(HiveSyncConfig config, int size) { + this(config, size, new DefaultDriverFactory(config)); + } + + // Package-private for tests: accepts a DriverFactory so unit tests can inject + // mock Driver instances without standing up a real Hive instance. + HiveDriverPool(HiveSyncConfig config, int size, DriverFactory factory) { + if (size < 1) { + throw new IllegalArgumentException("Pool size must be >= 1, got " + size); + } + this.size = size; + this.workers = new ArrayList<>(size); + String databaseName = config.getStringOrDefault(META_SYNC_DATABASE_NAME); + PoolThreadFactory threadFactory = new PoolThreadFactory(); + try { + // Bootstrap workers one at a time (not concurrently): each worker builds its + // own exclusively-owned SessionState, and constructing several SessionStates + // in parallel risks racing on shared scratch-dir creation. This only affects + // one-time pool startup cost, not per-statement dispatch latency. + for (int i = 0; i < size; i++) { + Worker worker = new Worker(threadFactory); + workers.add(worker); + worker.executor.submit(() -> { + worker.driver = factory.newDriver(databaseName); + worker.sessionState = SessionState.get(); + return null; + }).get(BOOTSTRAP_TIMEOUT_SECONDS, TimeUnit.SECONDS); + } + } catch (Exception e) { + tearDown(); + throw new HoodieException("Failed to construct HiveDriverPool of size " + size, e); + } + LOG.info("Initialized HiveDriverPool with {} workers", size); + } + + /** + * Runs each given SQL on <i>every</i> worker, in order. Used for setup statements + * (e.g. {@code USE database}) that must establish per-thread session context + * before any partition statement runs. Blocks until all workers have completed + * the setup. Throws on first error. + */ + public void runOnEachWorker(List<String> setupSqls) { + if (closed) { + throw new IllegalStateException("Cannot dispatch to a closed HiveDriverPool"); + } + if (setupSqls.isEmpty()) { + return; + } + List<Future<?>> futures = new ArrayList<>(workers.size()); + for (Worker worker : workers) { + futures.add(worker.executor.submit(() -> { + for (String sql : setupSqls) { + worker.driver.run(sql); + } + return null; + })); + } + awaitAll(futures); + } + + /** + * Dispatches each SQL string to a worker (round-robin) and returns the list of + * in-flight futures — this method does not block. The caller is responsible for + * awaiting completion via {@link #awaitAll(List)} and collecting errors. SQL text + * is intentionally not logged per-statement here: batched TOUCH/ADD statements can + * be many kilobytes, and N parallel workers would multiply the log volume. See + * {@link #awaitAll(List)} for the per-call summary log. + */ + public List<Future<?>> dispatchAll(List<String> sqls) { + if (closed) { + throw new IllegalStateException("Cannot dispatch to a closed HiveDriverPool"); + } + List<Future<?>> futures = new ArrayList<>(sqls.size()); + for (int i = 0; i < sqls.size(); i++) { + String sql = sqls.get(i); + Worker worker = workers.get(i % workers.size()); + futures.add(worker.executor.submit(() -> { + worker.driver.run(sql); + return null; + })); + } + return futures; + } + + /** + * Awaits all futures and throws the first exception encountered. On first failure, + * cancels the remaining (not yet started) futures so workers don't keep running + * pointless work after a fatal error. Any errors that finished before cancellation + * are logged at WARN. Callers do not need per-statement results (Hive's Driver.run + * side-effects the metastore), so this method is void. + */ + public void awaitAll(List<Future<?>> futures) { + long start = System.currentTimeMillis(); + Exception firstError = null; + int completed = 0; + int cancelled = 0; + for (int i = 0; i < futures.size(); i++) { + Future<?> f = futures.get(i); + try { + f.get(); + completed++; + } catch (CancellationException ce) { + // We cancelled this future ourselves after a prior error. Don't treat it + // as a new failure; just note it for the summary log. + cancelled++; + } catch (InterruptedException ie) { + Thread.currentThread().interrupt(); + if (firstError == null) { + firstError = ie; + cancelled += cancelRemaining(futures, i + 1); + } + } catch (ExecutionException ee) { + Exception cause = unwrap(ee); + if (firstError == null) { + firstError = cause; + cancelled += cancelRemaining(futures, i + 1); + } else { + LOG.warn("Additional SQL batch failed (suppressed in favor of first error)", cause); + } + } + } + if (firstError != null) { + throw new HoodieHiveSyncException("Failed in executing SQL", firstError); + } + LOG.info("Completed {} SQL statements ({} cancelled) in {} ms across {} workers", + completed, cancelled, System.currentTimeMillis() - start, size); + } + + private static int cancelRemaining(List<Future<?>> futures, int fromIndex) { + int cancelled = 0; + for (int j = fromIndex; j < futures.size(); j++) { + // mayInterruptIfRunning=false: the worker thread is bound to a Hive Driver + // whose state we don't want to corrupt mid-statement. Cancel only those that + // haven't started yet; in-flight statements run to completion. + if (futures.get(j).cancel(false)) { + cancelled++; + } + } + return cancelled; + } + + private static Exception unwrap(ExecutionException ee) { + Throwable cause = ee.getCause(); + return (cause instanceof Exception) ? (Exception) cause : ee; + } + + public int size() { + return size; + } + + @Override + public void close() { + if (closed) { + return; + } + closed = true; + tearDown(); + } + + private void tearDown() { + // Close each worker's own Driver and SessionState on its own thread, then shut + // the executor down. Each worker owns an exclusive SessionState (see + // DefaultDriverFactory), so there is no cross-worker close ordering to worry + // about here — closing worker i never affects worker j. + for (Worker worker : workers) { + try { + worker.executor.submit(() -> { + if (worker.driver != null) { + try { + worker.driver.close(); + } catch (Exception e) { + LOG.warn("Error closing pooled Driver", e); + } + } + if (worker.sessionState != null) { + try { + worker.sessionState.close(); + } catch (Exception e) { + LOG.warn("Error closing pooled SessionState", e); + } + } + return null; + }).get(30, TimeUnit.SECONDS); + } catch (Exception e) { + LOG.warn("Error during pool worker shutdown", e); + } + worker.executor.shutdown(); + try { + if (!worker.executor.awaitTermination(10, TimeUnit.SECONDS)) { + worker.executor.shutdownNow(); + } + } catch (InterruptedException ie) { + worker.executor.shutdownNow(); + Thread.currentThread().interrupt(); + } + } + workers.clear(); + } + + /** + * Per-slot state: a single-thread executor and the Driver + SessionState bound to + * its thread. Both are volatile because they are written by the bootstrap task and + * read by subsequent dispatch/teardown tasks on the same executor. + */ + private static final class Worker { + final ExecutorService executor; + volatile Driver driver; + volatile SessionState sessionState; + + Worker(ThreadFactory threadFactory) { + this.executor = Executors.newSingleThreadExecutor(threadFactory); + } + } + + @FunctionalInterface + interface DriverFactory { + Driver newDriver(String databaseName) throws Exception; + } + + /** + * Builds a real Hive {@link Driver} on the calling thread, backed by a + * {@link SessionState} that is exclusively owned by that thread (not shared with + * any other worker). Hive's session-scoped state (current database, scratch + * directories, and the transaction/lock manager under {@code DbTxnManager}) is + * mutated by {@code Driver.run()} and is not safe for concurrent use from multiple + * threads, so each worker must have its own instance. Bootstrap of all workers is + * done sequentially by the pool constructor specifically so these constructions + * don't race each other (e.g. on scratch-dir creation). + */ + private static final class DefaultDriverFactory implements DriverFactory { + private final HiveConf hiveConf; + + DefaultDriverFactory(HiveSyncConfig config) { + this.hiveConf = config.getHiveConf(); + } + + @Override + public Driver newDriver(String databaseName) throws Exception { + SessionState sessionState = new SessionState(hiveConf, Review Comment: Good catch. Fixed in 7e159fb — DefaultDriverFactory.newDriver now builds a per-worker HiveConf copy (new HiveConf(hiveConf)) and passes that copy to both SessionState and Driver, instead of sharing one HiveConf instance across all workers. ########## hudi-sync/hudi-hive-sync/src/main/java/org/apache/hudi/hive/HiveSyncConfigHolder.java: ########## @@ -122,6 +122,26 @@ public class HiveSyncConfigHolder { .defaultValue(1000) .markAdvanced() .withDocumentation("The number of partitions one batch when synchronous partitions to hive."); + public static final ConfigProperty<Boolean> HIVE_SYNC_BATCHING_ENABLED = ConfigProperty + .key("hoodie.datasource.hive_sync.batching.enabled") + .defaultValue(false) + .markAdvanced() + .sinceVersion("1.3.0") + .withDocumentation("Only applies to HiveQL sync mode. When true, TOUCH and SET_LOCATION partition " Review Comment: Fixed in 7e159fb — reworded to explicitly list ADD, TOUCH, and SET_LOCATION as dispatched in parallel, and clarified that only ADD'\''s batch size (not its dispatch) was already unchanged before this flag existed. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
