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/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.elasticsearch.indices;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.message.ParameterizedMessage;
import org.apache.lucene.store.AlreadyClosedException;
import org.elasticsearch.common.settings.Setting;
import org.elasticsearch.common.settings.Setting.Property;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.unit.ByteSizeUnit;
import org.elasticsearch.common.unit.ByteSizeValue;
import org.elasticsearch.common.unit.TimeValue;
import org.elasticsearch.common.util.concurrent.AbstractRunnable;
import org.elasticsearch.index.engine.Engine;
import org.elasticsearch.index.shard.IndexShard;
import org.elasticsearch.index.shard.IndexShardState;
import org.elasticsearch.index.shard.IndexingOperationListener;
import org.elasticsearch.index.shard.ShardId;
import org.elasticsearch.threadpool.Scheduler.Cancellable;
import org.elasticsearch.threadpool.ThreadPool;
import org.elasticsearch.threadpool.ThreadPool.Names;
import java.io.Closeable;
import java.util.ArrayList;
import java.util.EnumSet;
import java.util.HashSet;
import java.util.List;
import java.util.PriorityQueue;
import java.util.Set;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.locks.ReentrantLock;
public class IndexingMemoryController implements IndexingOperationListener, Closeable {
private static final Logger logger = LogManager.getLogger(IndexingMemoryController.class);
/** How much heap (% or bytes) we will share across all actively indexing shards on this node (default: 10%). */
public static final Setting INDEX_BUFFER_SIZE_SETTING =
Setting.memorySizeSetting("indices.memory.index_buffer_size", "10%", Property.NodeScope);
/** Only applies when indices.memory.index_buffer_size is a %,
* to set a floor on the actual size in bytes (default: 48 MB). */
public static final Setting MIN_INDEX_BUFFER_SIZE_SETTING = Setting.byteSizeSetting(
"indices.memory.min_index_buffer_size",
new ByteSizeValue(48, ByteSizeUnit.MB),
new ByteSizeValue(0, ByteSizeUnit.BYTES),
new ByteSizeValue(Long.MAX_VALUE, ByteSizeUnit.BYTES),
Property.NodeScope);
/** Only applies when indices.memory.index_buffer_size is a %,
* to set a ceiling on the actual size in bytes (default: not set). */
public static final Setting MAX_INDEX_BUFFER_SIZE_SETTING = Setting.byteSizeSetting(
"indices.memory.max_index_buffer_size",
new ByteSizeValue(-1),
new ByteSizeValue(-1),
new ByteSizeValue(Long.MAX_VALUE, ByteSizeUnit.BYTES),
Property.NodeScope);
/** If we see no indexing operations after this much time for a given shard,
* we consider that shard inactive (default: 5 minutes). */
public static final Setting SHARD_INACTIVE_TIME_SETTING = Setting.positiveTimeSetting(
"indices.memory.shard_inactive_time",
TimeValue.timeValueMinutes(5),
Property.NodeScope
);
/** How frequently we check indexing memory usage (default: 5 seconds). */
public static final Setting SHARD_MEMORY_INTERVAL_TIME_SETTING = Setting.positiveTimeSetting(
"indices.memory.interval",
TimeValue.timeValueSeconds(5),
Property.NodeScope);
private final ThreadPool threadPool;
private final Iterable indexShards;
private final ByteSizeValue indexingBuffer;
private final TimeValue inactiveTime;
private final TimeValue interval;
/** Contains shards currently being throttled because we can't write segments quickly enough */
private final Set throttled = new HashSet<>();
private final Cancellable scheduler;
private static final EnumSet CAN_WRITE_INDEX_BUFFER_STATES = EnumSet.of(
IndexShardState.RECOVERING, IndexShardState.POST_RECOVERY, IndexShardState.STARTED);
private final ShardsIndicesStatusChecker statusChecker;
IndexingMemoryController(Settings settings, ThreadPool threadPool, Iterable indexServices) {
this.indexShards = indexServices;
ByteSizeValue indexingBuffer = INDEX_BUFFER_SIZE_SETTING.get(settings);
String indexingBufferSetting = settings.get(INDEX_BUFFER_SIZE_SETTING.getKey());
// null means we used the default (10%)
if (indexingBufferSetting == null || indexingBufferSetting.endsWith("%")) {
// We only apply the min/max when % value was used for the index buffer:
ByteSizeValue minIndexingBuffer = MIN_INDEX_BUFFER_SIZE_SETTING.get(settings);
ByteSizeValue maxIndexingBuffer = MAX_INDEX_BUFFER_SIZE_SETTING.get(settings);
if (indexingBuffer.getBytes() < minIndexingBuffer.getBytes()) {
indexingBuffer = minIndexingBuffer;
}
if (maxIndexingBuffer.getBytes() != -1 && indexingBuffer.getBytes() > maxIndexingBuffer.getBytes()) {
indexingBuffer = maxIndexingBuffer;
}
}
this.indexingBuffer = indexingBuffer;
this.inactiveTime = SHARD_INACTIVE_TIME_SETTING.get(settings);
// we need to have this relatively small to free up heap quickly enough
this.interval = SHARD_MEMORY_INTERVAL_TIME_SETTING.get(settings);
this.statusChecker = new ShardsIndicesStatusChecker();
logger.debug("using indexing buffer size [{}] with {} [{}], {} [{}]",
this.indexingBuffer,
SHARD_INACTIVE_TIME_SETTING.getKey(), this.inactiveTime,
SHARD_MEMORY_INTERVAL_TIME_SETTING.getKey(), this.interval);
this.scheduler = scheduleTask(threadPool);
// Need to save this so we can later launch async "write indexing buffer to disk" on shards:
this.threadPool = threadPool;
}
protected Cancellable scheduleTask(ThreadPool threadPool) {
// it's fine to run it on the scheduler thread, no busy work
return threadPool.scheduleWithFixedDelay(statusChecker, interval, Names.SAME);
}
@Override
public void close() {
scheduler.cancel();
}
/**
* returns the current budget for the total amount of indexing buffers of
* active shards on this node
*/
ByteSizeValue indexingBufferSize() {
return indexingBuffer;
}
protected List availableShards() {
List availableShards = new ArrayList<>();
for (IndexShard shard : indexShards) {
if (CAN_WRITE_INDEX_BUFFER_STATES.contains(shard.state())) {
availableShards.add(shard);
}
}
return availableShards;
}
/** returns how much heap this shard is using for its indexing buffer */
protected long getIndexBufferRAMBytesUsed(IndexShard shard) {
return shard.getIndexBufferRAMBytesUsed();
}
/** returns how many bytes this shard is currently writing to disk */
protected long getShardWritingBytes(IndexShard shard) {
return shard.getWritingBytes();
}
/** ask this shard to refresh, in the background, to free up heap */
protected void writeIndexingBufferAsync(IndexShard shard) {
threadPool.executor(ThreadPool.Names.REFRESH).execute(new AbstractRunnable() {
@Override
public void doRun() {
shard.writeIndexingBuffer();
}
@Override
public void onFailure(Exception e) {
logger.warn(() -> new ParameterizedMessage("failed to write indexing buffer for shard [{}]; ignoring", shard.shardId()), e);
}
});
}
/** force checker to run now */
void forceCheck() {
statusChecker.run();
}
/** Asks this shard to throttle indexing to one thread */
protected void activateThrottling(IndexShard shard) {
shard.activateThrottling();
}
/** Asks this shard to stop throttling indexing to one thread */
protected void deactivateThrottling(IndexShard shard) {
shard.deactivateThrottling();
}
@Override
public void postIndex(ShardId shardId, Engine.Index index, Engine.IndexResult result) {
recordOperationBytes(index, result);
}
@Override
public void postDelete(ShardId shardId, Engine.Delete delete, Engine.DeleteResult result) {
recordOperationBytes(delete, result);
}
/** called by IndexShard to record estimated bytes written to translog for the operation */
private void recordOperationBytes(Engine.Operation operation, Engine.Result result) {
if (result.getResultType() == Engine.Result.Type.SUCCESS) {
statusChecker.bytesWritten(operation.estimatedSizeInBytes());
}
}
private static final class ShardAndBytesUsed implements Comparable {
final long bytesUsed;
final IndexShard shard;
ShardAndBytesUsed(long bytesUsed, IndexShard shard) {
this.bytesUsed = bytesUsed;
this.shard = shard;
}
@Override
public int compareTo(ShardAndBytesUsed other) {
// Sort larger shards first:
return Long.compare(other.bytesUsed, bytesUsed);
}
}
/** not static because we need access to many fields/methods from our containing class (IMC): */
final class ShardsIndicesStatusChecker implements Runnable {
final AtomicLong bytesWrittenSinceCheck = new AtomicLong();
final ReentrantLock runLock = new ReentrantLock();
/** Shard calls this on each indexing/delete op */
public void bytesWritten(int bytes) {
long totalBytes = bytesWrittenSinceCheck.addAndGet(bytes);
assert totalBytes >= 0;
while (totalBytes > indexingBuffer.getBytes()/30) {
if (runLock.tryLock()) {
try {
// Must pull this again because it may have changed since we first checked:
totalBytes = bytesWrittenSinceCheck.get();
if (totalBytes > indexingBuffer.getBytes()/30) {
bytesWrittenSinceCheck.addAndGet(-totalBytes);
// NOTE: this is only an approximate check, because bytes written is to the translog,
// vs indexing memory buffer which is typically smaller but can be larger in extreme
// cases (many unique terms). This logic is here only as a safety against thread
// starvation or too infrequent checking, to ensure we are still checking periodically,
// in proportion to bytes processed by indexing:
runUnlocked();
}
} finally {
runLock.unlock();
}
// Must get it again since other threads could have increased it while we were in runUnlocked
totalBytes = bytesWrittenSinceCheck.get();
} else {
// Another thread beat us to it: let them do all the work, yay!
break;
}
}
}
@Override
public void run() {
runLock.lock();
try {
runUnlocked();
} finally {
runLock.unlock();
}
}
private void runUnlocked() {
// NOTE: even if we hit an errant exc here, our ThreadPool.scheduledWithFixedDelay will log the exception and re-invoke us
// again, on schedule
// First pass to sum up how much heap all shards' indexing buffers are using now, and how many bytes they are currently moving
// to disk:
long totalBytesUsed = 0;
long totalBytesWriting = 0;
for (IndexShard shard : availableShards()) {
// Give shard a chance to transition to inactive so sync'd flush can happen:
checkIdle(shard, inactiveTime.nanos());
// How many bytes this shard is currently (async'd) moving from heap to disk:
long shardWritingBytes = getShardWritingBytes(shard);
// How many heap bytes this shard is currently using
long shardBytesUsed = getIndexBufferRAMBytesUsed(shard);
shardBytesUsed -= shardWritingBytes;
totalBytesWriting += shardWritingBytes;
// If the refresh completed just after we pulled shardWritingBytes and before we pulled shardBytesUsed, then we could
// have a negative value here. So we just skip this shard since that means it's now using very little heap:
if (shardBytesUsed < 0) {
continue;
}
totalBytesUsed += shardBytesUsed;
}
if (logger.isTraceEnabled()) {
logger.trace("total indexing heap bytes used [{}] vs {} [{}], currently writing bytes [{}]",
new ByteSizeValue(totalBytesUsed), INDEX_BUFFER_SIZE_SETTING.getKey(), indexingBuffer,
new ByteSizeValue(totalBytesWriting));
}
// If we are using more than 50% of our budget across both indexing buffer and bytes we are still moving to disk, then we now
// throttle the top shards to send back-pressure to ongoing indexing:
boolean doThrottle = (totalBytesWriting + totalBytesUsed) > 1.5 * indexingBuffer.getBytes();
if (totalBytesUsed > indexingBuffer.getBytes()) {
// OK we are now over-budget; fill the priority queue and ask largest shard(s) to refresh:
PriorityQueue queue = new PriorityQueue<>();
for (IndexShard shard : availableShards()) {
// How many bytes this shard is currently (async'd) moving from heap to disk:
long shardWritingBytes = getShardWritingBytes(shard);
// How many heap bytes this shard is currently using
long shardBytesUsed = getIndexBufferRAMBytesUsed(shard);
// Only count up bytes not already being refreshed:
shardBytesUsed -= shardWritingBytes;
// If the refresh completed just after we pulled shardWritingBytes and before we pulled shardBytesUsed, then we could
// have a negative value here. So we just skip this shard since that means it's now using very little heap:
if (shardBytesUsed < 0) {
continue;
}
if (shardBytesUsed > 0) {
if (logger.isTraceEnabled()) {
if (shardWritingBytes != 0) {
logger.trace("shard [{}] is using [{}] heap, writing [{}] heap", shard.shardId(), shardBytesUsed,
shardWritingBytes);
} else {
logger.trace("shard [{}] is using [{}] heap, not writing any bytes", shard.shardId(), shardBytesUsed);
}
}
queue.add(new ShardAndBytesUsed(shardBytesUsed, shard));
}
}
logger.debug("now write some indexing buffers: total indexing heap bytes used [{}] vs {} [{}], " +
"currently writing bytes [{}], [{}] shards with non-zero indexing buffer", new ByteSizeValue(totalBytesUsed),
INDEX_BUFFER_SIZE_SETTING.getKey(), indexingBuffer, new ByteSizeValue(totalBytesWriting), queue.size());
while (totalBytesUsed > indexingBuffer.getBytes() && queue.isEmpty() == false) {
ShardAndBytesUsed largest = queue.poll();
logger.debug("write indexing buffer to disk for shard [{}] to free up its [{}] indexing buffer",
largest.shard.shardId(), new ByteSizeValue(largest.bytesUsed));
writeIndexingBufferAsync(largest.shard);
totalBytesUsed -= largest.bytesUsed;
if (doThrottle && throttled.contains(largest.shard) == false) {
logger.info("now throttling indexing for shard [{}]: segment writing can't keep up", largest.shard.shardId());
throttled.add(largest.shard);
activateThrottling(largest.shard);
}
}
}
if (doThrottle == false) {
for(IndexShard shard : throttled) {
logger.info("stop throttling indexing for shard [{}]", shard.shardId());
deactivateThrottling(shard);
}
throttled.clear();
}
}
}
/**
* ask this shard to check now whether it is inactive, and reduces its indexing buffer if so.
*/
protected void checkIdle(IndexShard shard, long inactiveTimeNS) {
try {
shard.checkIdle(inactiveTimeNS);
} catch (AlreadyClosedException e) {
logger.trace(() -> new ParameterizedMessage("ignore exception while checking if shard {} is inactive", shard.shardId()), e);
}
}
}
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