This is an automated email from the ASF dual-hosted git repository.
clebertsuconic pushed a commit to branch 2.6.x
in repository https://gitbox.apache.org/repos/asf/activemq-artemis.git
commit 87ddafc13d78605814c486178b39037df42ca3a0
Author: Michael André Pearce <michael.andre.pea...@me.com>
AuthorDate: Wed Jan 23 09:59:15 2019 +0000
ARTEMIS-2236 Address Latency Impact caused by ARTEMIS-1451
Readdress ARTEMIS-1451 concern of sync blocks, remove synchronization by
simplifying original code and using atomics.
(cherry picked from commit d4c41e45bc762f2d8b7831529678bc4061bf9cd3)
---
.../artemis/utils/ActiveMQThreadPoolExecutor.java | 55 ++++++----------------
1 file changed, 15 insertions(+), 40 deletions(-)
diff --git
a/artemis-commons/src/main/java/org/apache/activemq/artemis/utils/ActiveMQThreadPoolExecutor.java
b/artemis-commons/src/main/java/org/apache/activemq/artemis/utils/ActiveMQThreadPoolExecutor.java
index c3b1988..da7de12 100755
---
a/artemis-commons/src/main/java/org/apache/activemq/artemis/utils/ActiveMQThreadPoolExecutor.java
+++
b/artemis-commons/src/main/java/org/apache/activemq/artemis/utils/ActiveMQThreadPoolExecutor.java
@@ -20,6 +20,7 @@ import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
/*
* ActiveMQThreadPoolExecutor: a special ThreadPoolExecutor that combines
@@ -46,15 +47,13 @@ public class ActiveMQThreadPoolExecutor extends
ThreadPoolExecutor {
private ActiveMQThreadPoolExecutor executor = null;
- // lock object to synchronize on
- private final Object lock = new Object();
-
// keep track of the difference between the number of idle threads and
// the number of queued tasks. If the delta is > 0, we have more
// idle threads than queued tasks and can add more tasks into the queue.
// The delta is incremented if a thread becomes idle or if a task is
taken from the queue.
// The delta is decremented if a thread leaves idle state or if a task
is added to the queue.
- private int threadTaskDelta = 0;
+ private static final AtomicIntegerFieldUpdater<ThreadPoolQueue>
DELTA_UPDATER = AtomicIntegerFieldUpdater.newUpdater(ThreadPoolQueue.class,
"threadTaskDelta");
+ private volatile int threadTaskDelta = 0;
public void setExecutor(ActiveMQThreadPoolExecutor executor) {
this.executor = executor;
@@ -64,20 +63,15 @@ public class ActiveMQThreadPoolExecutor extends
ThreadPoolExecutor {
public boolean offer(Runnable runnable) {
boolean retval = false;
- // Need to lock for 2 reasons:
- // 1. to safely handle poll timeouts
- // 2. to protect the delta from parallel updates
- synchronized (lock) {
- if ((executor.getPoolSize() >= executor.getMaximumPoolSize()) ||
(threadTaskDelta > 0)) {
- // A new task will be added to the queue if the maximum number
of threads has been reached
- // or if the delta is > 0, which means that there are enough
idle threads.
+ if (threadTaskDelta > 0 || (executor.getPoolSize() >=
executor.getMaximumPoolSize())) {
+ // A new task will be added to the queue if the maximum number of
threads has been reached
+ // or if the delta is > 0, which means that there are enough idle
threads.
- retval = super.offer(runnable);
+ retval = super.offer(runnable);
- // Only decrement the delta if the task has actually been added
to the queue
- if (retval)
- threadTaskDelta--;
- }
+ // Only decrement the delta if the task has actually been added to
the queue
+ if (retval)
+ DELTA_UPDATER.decrementAndGet(this);
}
return retval;
@@ -87,9 +81,8 @@ public class ActiveMQThreadPoolExecutor extends
ThreadPoolExecutor {
public Runnable take() throws InterruptedException {
// Increment the delta as a thread becomes idle
// by waiting for a task to take from the queue
- synchronized (lock) {
- threadTaskDelta++;
- }
+ DELTA_UPDATER.incrementAndGet(this);
+
Runnable runnable = null;
@@ -102,9 +95,7 @@ public class ActiveMQThreadPoolExecutor extends
ThreadPoolExecutor {
// (decremented by the thread and incremented by the taken task)
// Only if no task had been taken, we have to decrement the delta.
if (runnable == null) {
- synchronized (lock) {
- threadTaskDelta--;
- }
+ DELTA_UPDATER.decrementAndGet(this);
}
}
}
@@ -113,34 +104,18 @@ public class ActiveMQThreadPoolExecutor extends
ThreadPoolExecutor {
public Runnable poll(long arg0, TimeUnit arg2) throws
InterruptedException {
// Increment the delta as a thread becomes idle
// by waiting for a task to poll from the queue
- synchronized (lock) {
- threadTaskDelta++;
- }
+ DELTA_UPDATER.incrementAndGet(this);
Runnable runnable = null;
- boolean timedOut = false;
try {
runnable = super.poll(arg0, arg2);
- timedOut = (runnable == null);
} finally {
// Now the thread is no longer idle waiting for a task
// If it had taken a task, the delta remains the same
// (decremented by the thread and incremented by the taken task)
if (runnable == null) {
- synchronized (lock) {
- // If the poll called timed out, we check again within a
synchronized block
- // to make sure all offer calls have been completed.
- // This is to handle a newly queued task if the timeout
occurred while an offer call
- // added that task to the queue instead of creating a new
thread.
- if (timedOut)
- runnable = super.poll();
-
- // Only if no task had been taken (either no timeout, or no
task from after-timeout poll),
- // we have to decrement the delta.
- if (runnable == null)
- threadTaskDelta--;
- }
+ DELTA_UPDATER.decrementAndGet(this);
}
}
