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https://issues.apache.org/jira/browse/ACCUMULO-4187?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15238575#comment-15238575
]
ASF GitHub Bot commented on ACCUMULO-4187:
------------------------------------------
Github user joshelser commented on a diff in the pull request:
https://github.com/apache/accumulo/pull/90#discussion_r59490681
--- Diff:
server/base/src/main/java/org/apache/accumulo/server/util/ratelimit/SharedRateLimiterFactory.java
---
@@ -0,0 +1,152 @@
+/*
+ * 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.accumulo.server.util.ratelimit;
+
+import com.google.common.collect.ImmutableList;
+import java.util.List;
+import java.util.WeakHashMap;
+import java.util.concurrent.Callable;
+import java.util.concurrent.atomic.LongAdder;
+import org.apache.accumulo.core.conf.AccumuloConfiguration;
+import org.apache.accumulo.core.util.ratelimit.GuavaRateLimiter;
+import org.apache.accumulo.core.util.ratelimit.RateLimiter;
+import org.apache.accumulo.server.util.time.SimpleTimer;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class SharedRateLimiterFactory {
+ private static final long REPORT_RATE = 60000;
+ private static final long UPDATE_RATE = 1000;
+ private static SharedRateLimiterFactory instance = null;
+ private final Logger logger =
LoggerFactory.getLogger(SharedRateLimiterFactory.class);
+ private final WeakHashMap<String,SharedRateLimiter> activeLimiters = new
WeakHashMap<>();
+
+ private SharedRateLimiterFactory() {}
+
+ public static SharedRateLimiterFactory getInstance(SimpleTimer timer) {
+ synchronized (SharedRateLimiterFactory.class) {
+ if (instance == null) {
+ instance = new SharedRateLimiterFactory();
+
+ // Update periodically
+ timer.schedule(new Runnable() {
+ @Override
+ public void run() {
+ instance.update();
+ }
+ }, UPDATE_RATE, UPDATE_RATE);
+
+ // Report periodically
+ timer.schedule(new Runnable() {
+ @Override
+ public void run() {
+ instance.report();
+ }
+ }, REPORT_RATE, REPORT_RATE);
+ }
+ return instance;
+ }
+ }
+
+ public static SharedRateLimiterFactory getInstance(AccumuloConfiguration
conf) {
+ return getInstance(SimpleTimer.getInstance(conf));
+ }
+
+ /**
+ * Lookup the RateLimiter associated with the specified name, or create
a new one for that name. RateLimiters should be closed when no longer needed.
+ *
+ * @param name
+ * key for the rate limiter
+ * @param rateGenerator
+ * a function which can be called to get what the current rate
for the rate limiter should be.
+ */
+ public RateLimiter create(String name, Callable<Long> rateGenerator) {
+ synchronized (activeLimiters) {
+ if (activeLimiters.containsKey(name)) {
+ SharedRateLimiter limiter = activeLimiters.get(name);
+ return limiter;
+ } else {
+ long initialRate;
+ try {
+ initialRate = rateGenerator.call();
+ } catch (Exception ex) {
+ throw new IllegalStateException(ex);
+ }
+ SharedRateLimiter limiter = new SharedRateLimiter(name,
rateGenerator, initialRate);
+ activeLimiters.put(name, limiter);
+ return limiter;
+ }
+ }
+ }
+
+ protected void update() {
+ List<SharedRateLimiter> limiters;
+ synchronized (activeLimiters) {
+ limiters = ImmutableList.copyOf(activeLimiters.values());
+ }
+ for (SharedRateLimiter limiter : limiters) {
+ limiter.update();
+ }
+ }
+
+ protected void report() {
+ List<SharedRateLimiter> limiters;
+ synchronized (activeLimiters) {
+ limiters = ImmutableList.copyOf(activeLimiters.values());
+ }
+ for (SharedRateLimiter limiter : limiters) {
+ limiter.report();
+ }
+ }
+
+ protected class SharedRateLimiter extends GuavaRateLimiter {
+ private final LongAdder permitsAcquired = new LongAdder();
+ private final Callable<Long> rateCallable;
+ private final String name;
+
+ SharedRateLimiter(String name, Callable<Long> rateCallable, long
initialRate) {
+ super(initialRate);
+ this.name = name;
+ this.rateCallable = rateCallable;
+ }
+
+ @Override
+ public void acquire(long permits) {
+ super.acquire(permits);
+ permitsAcquired.add(permits);
+ }
+
+ public void update() {
+ try {
+ // Reset rate if needed
+ long rate = rateCallable.call();
+ if (rate != getRate()) {
+ setRate(rate);
+ }
+ } catch (Exception ex) {
+ logger.debug("Failed to update rate limiter", ex);
+ }
+ }
+
+ public void report() {
+ long sum = permitsAcquired.sumThenReset();
+ if (sum > 0) {
+ logger.debug(String.format("RateLimiter '%s': %,d of %,d
permits/second", name, sum * 1000L / REPORT_RATE, getRate()));
--- End diff --
Wrap this in a `logger.ifDebugIsEnabled()` conditional, please. Typically,
Logger instances are named `log` not `logger`. You could also do the string
formatting "natively" with SLF4J's `{}` replacement syntax.
> Rate limiting of major compactions
> ----------------------------------
>
> Key: ACCUMULO-4187
> URL: https://issues.apache.org/jira/browse/ACCUMULO-4187
> Project: Accumulo
> Issue Type: Improvement
> Components: core, tserver
> Affects Versions: 1.8.0
> Reporter: Shawn Walker
> Assignee: Shawn Walker
> Priority: Minor
> Fix For: 1.8.0
>
>
> In discussing [ACCUMULO-4166] with Keith Turner, we decided that the
> underlying issue is that major compactions can overwhelm a tablet server,
> rendering it nearly unresponsive.
> To address this, we should take a cue from Apache Cassandra and restrict how
> quickly we perform major compactions. Rate limiting reads and writes
> involved in major compactions will directly affect the IO load caused by
> major compactions, and should also indirectly affect the CPU load.
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