andreacavalli/netty5
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Revamp the selector auto rebuild checker

Browse Source 
- Count the number of select() calls made to wait until reaching at the expected dead line, and rebuild selectors if too many select() calls were made.
This commit is contained in:
Trustin Lee 2013-03-22 14:33:47 +09:00
parent 69e5a0eb9c
commit 19ffdd5c29
3 changed files with 53 additions and 74 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
common/src/main/java/io/netty/util/concurrent/SingleThreadEventExecutor.java
View File

@ -352,26 +352,13 @@ public abstract class SingleThreadEventExecutor extends AbstractEventExecutor {
/**
* Returns the ammount of time left until the scheduled task with the closest dead line is executed.
*/
protected long delayNanos() {
protected long delayNanos(long currentTimeNanos) {
ScheduledFutureTask<?> delayedTask = delayedTaskQueue.peek();
if (delayedTask == null) {
return SCHEDULE_PURGE_INTERVAL;
}
return delayedTask.delayNanos();
}
/**
* Returns the ammount of time left until the scheduled task with the closest dead line is executed.
*/
protected long delayMillis() {
long delayNanos = delayNanos();
long delayMillis = delayNanos / 1000000L;
if (delayNanos % 1000000L < 500000L) {
return delayMillis;
} else {
return delayMillis + 1;
}
return delayedTask.delayNanos(currentTimeNanos);
}
/**
@ -763,6 +750,10 @@ public abstract class SingleThreadEventExecutor extends AbstractEventExecutor {
return Math.max(0, deadlineNanos() - nanoTime());
}
public long delayNanos(long currentTimeNanos) {
return Math.max(0, deadlineNanos() - (currentTimeNanos - START_TIME));
}
@Override
public long getDelay(TimeUnit unit) {
return unit.convert(delayNanos(), TimeUnit.NANOSECONDS);

104
transport/src/main/java/io/netty/channel/nio/NioEventLoop.java
View File

@ -77,7 +77,7 @@ public final class NioEventLoop extends SingleThreadEventLoop {
}
}
int selectorAutoRebuildThreshold = SystemPropertyUtil.getInt("io.netty.selectorAutoRebuildThreshold", 16);
int selectorAutoRebuildThreshold = SystemPropertyUtil.getInt("io.netty.selectorAutoRebuildThreshold", 512);
if (selectorAutoRebuildThreshold < MIN_PREMATURE_SELECTOR_RETURNS) {
selectorAutoRebuildThreshold = 0;
}
@ -108,7 +108,6 @@ public final class NioEventLoop extends SingleThreadEventLoop {
private volatile int ioRatio = 50;
private int cancelledKeys;
private boolean needsToSelectAgain;
private int prematureSelectorReturns;
NioEventLoop(
NioEventLoopGroup parent, ThreadFactory threadFactory, SelectorProvider selectorProvider) {
@ -121,7 +120,6 @@ public final class NioEventLoop extends SingleThreadEventLoop {
}
private Selector openSelector() {
resetPrematureSelectorReturns();
try {
return provider.openSelector();
} catch (IOException e) {
@ -548,9 +546,7 @@ public final class NioEventLoop extends SingleThreadEventLoop {
void selectNow() throws IOException {
try {
if (selector.selectNow() != 0) {
resetPrematureSelectorReturns();
}
selector.selectNow();
} finally {
// restore wakup state if needed
if (wakenUp.get()) {
@ -561,48 +557,52 @@ public final class NioEventLoop extends SingleThreadEventLoop {
private void select() throws IOException {
Selector selector = this.selector;
long delayMillis = delayMillis();
try {
if (delayMillis > 0) {
long startTimeNanos = System.nanoTime();
if (selector.select(delayMillis) == 0) {
if (oldWakenUp || wakenUp.get() || hasTasks()) {
// Waken up by user or the task queue has a pending task.
return;
int selectCnt = 0;
long currentTimeNanos = System.nanoTime();
long selectDeadLineNanos = currentTimeNanos + delayNanos(currentTimeNanos);
for (;;) {
long timeoutMillis = (selectDeadLineNanos - currentTimeNanos + 500000L) / 1000000L;
if (timeoutMillis <= 0) {
if (selectCnt == 0) {
selector.selectNow();
selectCnt = 1;
}
long delayNanos = delayNanos();
if (delayNanos <= 0) {
// Waken up to handle a delayed task.
return;
}
if (System.nanoTime() - startTimeNanos < delayNanos >>> 1) {
// Returned way before the specified timeout with no selected keys.
// This may be because of the JDK /dev/epoll bug - increment the counter.
prematureSelectorReturns ++;
if (SELECTOR_AUTO_REBUILD_THRESHOLD > 0 &&
prematureSelectorReturns >= SELECTOR_AUTO_REBUILD_THRESHOLD) {
// The selector returned prematurely many times in a row.
// Rebuild the selector to work around the problem.
logger.warn(
"Selector.select() returned prematurely {} times in a row; rebuilding selector.",
prematureSelectorReturns);
rebuildSelector();
// Select again to populate selectedKeys.
selector.selectNow();
}
} else {
resetPrematureSelectorReturns();
}
} else {
resetPrematureSelectorReturns();
break;
}
} else {
if (selector.selectNow() != 0) {
resetPrematureSelectorReturns();
int selectedKeys = selector.select(timeoutMillis);
selectCnt ++;
if (selectedKeys != 0 || oldWakenUp || wakenUp.get() || hasTasks()) {
// Selected something,
// waken up by user, or
// the task queue has a pending task.
break;
}
if (SELECTOR_AUTO_REBUILD_THRESHOLD > 0 &&
selectCnt >= SELECTOR_AUTO_REBUILD_THRESHOLD) {
// The selector returned prematurely many times in a row.
// Rebuild the selector to work around the problem.
logger.warn(
"Selector.select() returned prematurely {} times in a row; rebuilding selector.",
selectCnt);
rebuildSelector();
// Select again to populate selectedKeys.
selector.selectNow();
selectCnt = 1;
break;
}
currentTimeNanos = System.nanoTime();
}
if (selectCnt > MIN_PREMATURE_SELECTOR_RETURNS) {
if (logger.isDebugEnabled()) {
logger.debug("Selector.select() returned prematurely {} times in a row.", selectCnt - 1);
}
}
} catch (CancelledKeyException e) {
@ -616,21 +616,9 @@ public final class NioEventLoop extends SingleThreadEventLoop {
private void selectAgain() {
needsToSelectAgain = false;
try {
if (selector.selectNow() != 0) {
resetPrematureSelectorReturns();
}
selector.selectNow();
} catch (Throwable t) {
logger.warn("Failed to update SelectionKeys.", t);
}
}
private void resetPrematureSelectorReturns() {
int prematureSelectorReturns = this.prematureSelectorReturns;
if (prematureSelectorReturns >= MIN_PREMATURE_SELECTOR_RETURNS) {
if (logger.isDebugEnabled()) {
logger.debug("Selector.select() returned prematurely {} times in a row.", prematureSelectorReturns);
}
this.prematureSelectorReturns = 0;
}
}
}

2
transport/src/test/java/io/netty/channel/SingleThreadEventLoopTest.java
View File

@ -377,7 +377,7 @@ public class SingleThreadEventLoopTest {
protected void run() {
for (;;) {
try {
Thread.sleep(TimeUnit.NANOSECONDS.toMillis(delayNanos()));
Thread.sleep(TimeUnit.NANOSECONDS.toMillis(delayNanos(System.nanoTime())));
} catch (InterruptedException e) {
// Waken up by interruptThread()
}