@Override
public synchronized void merge(IndexWriter writer, MergeTrigger trigger, boolean newMergesFound)
throws IOException {
assert !Thread.holdsLock(writer);
initDynamicDefaults(writer);
if (trigger == MergeTrigger.CLOSING) {
// Disable throttling on close:
targetMBPerSec = MAX_MERGE_MB_PER_SEC;
updateMergeThreads();
}
// First, quickly run through the newly proposed merges
// and add any orthogonal merges (ie a merge not
// involving segments already pending to be merged) to
// the queue. If we are way behind on merging, many of
// these newly proposed merges will likely already be
// registered.
if (verbose()) {
message("now merge");
message(" index: " + writer.segString());
}
// Iterate, pulling from the IndexWriter's queue of
// pending merges, until it's empty:
while (true) {
if (maybeStall(writer) == false) {
break;
}
OneMerge merge = writer.getNextMerge();
if (merge == null) {
if (verbose()) {
message(" no more merges pending; now return");
}
return;
}
updateIOThrottle(merge);
boolean success = false;
try {
if (verbose()) {
message(" consider merge " + writer.segString(merge.segments));
}
// OK to spawn a new merge thread to handle this
// merge:
final MergeThread merger = getMergeThread(writer, merge);
mergeThreads.add(merger);
if (verbose()) {
message(" launch new thread [" + merger.getName() + "]");
}
merger.start();
updateMergeThreads();
success = true;
} finally {
if (!success) {
writer.mergeFinish(merge);
}
}
}
}
/**
* Called whenever the running merges have changed, to set merge IO limits. This method sorts the
* merge threads by their merge size in descending order and then pauses/unpauses threads from
* first to last -- that way, smaller merges are guaranteed to run before larger ones.
*/
protected synchronized void updateMergeThreads() {
// Only look at threads that are alive & not in the
// process of stopping (ie have an active merge):
final List<MergeThread> activeMerges = new ArrayList<>();
int threadIdx = 0;
while (threadIdx < mergeThreads.size()) {
final MergeThread mergeThread = mergeThreads.get(threadIdx);
if (!mergeThread.isAlive()) {
// Prune any dead threads
mergeThreads.remove(threadIdx);
continue;
}
activeMerges.add(mergeThread);
threadIdx++;
}
// Sort the merge threads, largest first:
CollectionUtil.timSort(activeMerges);
final int activeMergeCount = activeMerges.size();
int bigMergeCount = 0;
for (threadIdx = activeMergeCount - 1; threadIdx >= 0; threadIdx--) {
MergeThread mergeThread = activeMerges.get(threadIdx);
if (mergeThread.merge.estimatedMergeBytes > MIN_BIG_MERGE_MB * 1024 * 1024) {
bigMergeCount = 1 + threadIdx;
break;
}
}
long now = System.nanoTime();
StringBuilder message;
if (verbose()) {
message = new StringBuilder();
message.append(
String.format(
Locale.ROOT,
"updateMergeThreads ioThrottle=%s targetMBPerSec=%.1f MB/sec",
doAutoIOThrottle,
targetMBPerSec));
} else {
message = null;
}
for (threadIdx = 0; threadIdx < activeMergeCount; threadIdx++) {
MergeThread mergeThread = activeMerges.get(threadIdx);
OneMerge merge = mergeThread.merge;
// pause the thread if maxThreadCount is smaller than the number of merge threads.
final boolean doPause = threadIdx < bigMergeCount - maxThreadCount;
double newMBPerSec;
if (doPause) {
newMBPerSec = 0.0;
} else if (merge.maxNumSegments != -1) {
newMBPerSec = forceMergeMBPerSec;
} else if (doAutoIOThrottle == false) {
newMBPerSec = Double.POSITIVE_INFINITY;
} else if (merge.estimatedMergeBytes < MIN_BIG_MERGE_MB * 1024 * 1024) {
// Don't rate limit small merges:
newMBPerSec = Double.POSITIVE_INFINITY;
} else {
newMBPerSec = targetMBPerSec;
}
double curMBPerSec = merge.rateLimiter.getMBPerSec();
if (verbose()) {
long mergeStartNS = merge.mergeStartNS;
if (mergeStartNS == -1) {
// IndexWriter didn't start the merge yet:
mergeStartNS = now;
}
message.append('\n');
message.append(
String.format(
Locale.ROOT,
"merge thread %s estSize=%.1f MB (written=%.1f MB) runTime=%.1fs (stopped=%.1fs, paused=%.1fs) rate=%s\n",
mergeThread.getName(),
bytesToMB(merge.estimatedMergeBytes),
bytesToMB(merge.rateLimiter.totalBytesWritten),
nsToSec(now - mergeStartNS),
nsToSec(merge.rateLimiter.getTotalStoppedNS()),
nsToSec(merge.rateLimiter.getTotalPausedNS()),
rateToString(merge.rateLimiter.getMBPerSec())));
if (newMBPerSec != curMBPerSec) {
if (newMBPerSec == 0.0) {
message.append(" now stop");
} else if (curMBPerSec == 0.0) {
if (newMBPerSec == Double.POSITIVE_INFINITY) {
message.append(" now resume");
} else {
message.append(
String.format(Locale.ROOT, " now resume to %.1f MB/sec", newMBPerSec));
}
} else {
message.append(
String.format(
Locale.ROOT,
" now change from %.1f MB/sec to %.1f MB/sec",
curMBPerSec,
newMBPerSec));
}
} else if (curMBPerSec == 0.0) {
message.append(" leave stopped");
} else {
message.append(String.format(Locale.ROOT, " leave running at %.1f MB/sec", curMBPerSec));
}
}
merge.rateLimiter.setMBPerSec(newMBPerSec);
}
if (verbose()) {
message(message.toString());
}
}