7169050: (se) Selector.select slow on Solaris due to insertion of POLLREMOVE and 0 events
Reviewed-by: chegar, coffeys
This commit is contained in:
Alan Bateman
parent
380c23f06b
commit
e1774fc7a1
@ -25,9 +25,7 @@
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package sun.nio.ch;
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import sun.misc.*;
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import java.io.IOException;
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import java.util.LinkedList;
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/**
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@ -66,6 +64,9 @@ class DevPollArrayWrapper {
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static final short EVENT_OFFSET = 4;
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static final short REVENT_OFFSET = 6;
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// Special value to indicate that an update should be ignored
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static final byte CANCELLED = (byte)-1;
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// Maximum number of open file descriptors
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static final int OPEN_MAX = fdLimit();
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@ -74,13 +75,16 @@ class DevPollArrayWrapper {
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static final int NUM_POLLFDS = Math.min(OPEN_MAX-1, 8192);
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// Base address of the native pollArray
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private long pollArrayAddress;
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private final long pollArrayAddress;
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// Array of pollfd structs used for driver updates
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private AllocatedNativeObject updatePollArray;
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private final AllocatedNativeObject updatePollArray;
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// Maximum number of POLL_FD structs to update at once
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private int MAX_UPDATE_SIZE = Math.min(OPEN_MAX, 10000);
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private final int MAX_UPDATE_SIZE = Math.min(OPEN_MAX, 512);
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// Initial size of arrays for fd registration changes
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private final int INITIAL_PENDING_UPDATE_SIZE = 64;
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DevPollArrayWrapper() {
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int allocationSize = NUM_POLLFDS * SIZE_POLLFD;
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@ -91,19 +95,6 @@ class DevPollArrayWrapper {
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wfd = init();
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}
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// Machinery for remembering fd registration changes
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// A hashmap could be used but the number of changes pending
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// is expected to be small
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private static class Updator {
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int fd;
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int mask;
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Updator(int fd, int mask) {
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this.fd = fd;
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this.mask = mask;
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}
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}
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private LinkedList<Updator> updateList = new LinkedList<Updator>();
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// The pollfd array for results from devpoll driver
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private AllocatedNativeObject pollArray;
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@ -122,6 +113,20 @@ class DevPollArrayWrapper {
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// Number of updated pollfd entries
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int updated;
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// object to synchronize fd registration changes
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private final Object updateLock = new Object();
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// number of file descriptors with registration changes pending
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private int updateCount;
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// file descriptors with registration changes pending
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private int[] updateDescriptors = new int[INITIAL_PENDING_UPDATE_SIZE];
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// events for file descriptors with registration changes pending, indexed
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// by file descriptor and stored as bytes for efficiency reasons.
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private byte[] updateEvents = new byte[OPEN_MAX];
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void initInterrupt(int fd0, int fd1) {
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outgoingInterruptFD = fd1;
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incomingInterruptFD = fd0;
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@ -149,14 +154,32 @@ class DevPollArrayWrapper {
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}
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void setInterest(int fd, int mask) {
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synchronized (updateList) {
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updateList.add(new Updator(fd, mask));
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synchronized (updateLock) {
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// record the file descriptor and events, expanding the
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// respective arrays first if necessary.
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int oldCapacity = updateDescriptors.length;
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if (updateCount >= oldCapacity) {
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int newCapacity = oldCapacity + INITIAL_PENDING_UPDATE_SIZE;
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int[] newDescriptors = new int[newCapacity];
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System.arraycopy(updateDescriptors, 0, newDescriptors, 0, oldCapacity);
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updateDescriptors = newDescriptors;
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}
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updateDescriptors[updateCount++] = fd;
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// events are stored as bytes for efficiency reasons
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byte b = (byte)mask;
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assert (b == mask) && (b != CANCELLED);
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updateEvents[fd] = b;
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}
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}
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void release(int fd) {
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synchronized (updateList) {
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updateList.add(new Updator(fd, POLLREMOVE));
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synchronized (updateLock) {
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// cancel any pending update for this file descriptor
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updateEvents[fd] = CANCELLED;
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// remove from /dev/poll
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register(wfd, fd, POLLREMOVE);
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}
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}
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@ -181,32 +204,37 @@ class DevPollArrayWrapper {
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void updateRegistrations() throws IOException {
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// Populate pollfd array with updated masks
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synchronized (updateList) {
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while (updateList.size() > 0) {
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// We have to insert a dummy node in between each
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// real update to use POLLREMOVE on the fd first because
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// otherwise the changes are simply OR'd together
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int index = 0;
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Updator u = null;
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while ((u = updateList.poll()) != null) {
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// First add pollfd struct to clear out this fd
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putPollFD(updatePollArray, index, u.fd, POLLREMOVE);
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index++;
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// Now add pollfd to update this fd, if necessary
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if (u.mask != POLLREMOVE) {
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putPollFD(updatePollArray, index, u.fd, (short)u.mask);
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index++;
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}
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synchronized (updateLock) {
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// Check against the max update size; these are
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// all we will process. Valid index ranges from 0 to
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// (MAX_UPDATE_SIZE - 1) and we can use up to 2 per loop
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if (index > MAX_UPDATE_SIZE - 2)
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break;
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int j = 0;
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int index = 0;
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while (j < updateCount) {
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int fd = updateDescriptors[j];
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short events = updateEvents[fd];
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// skip update if key has been cancelled
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if (events != CANCELLED) {
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// remove from /dev/poll when the interest ops changes to 0
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if (events == 0)
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events = POLLREMOVE;
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// populate pollfd array with updated event
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putPollFD(updatePollArray, index, fd, events);
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index++;
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if (index >= MAX_UPDATE_SIZE) {
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registerMultiple(wfd, updatePollArray.address(), index);
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index = 0;
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}
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}
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// Register the changes with /dev/poll
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j++;
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}
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// write any remaining updates
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if (index > 0)
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registerMultiple(wfd, updatePollArray.address(), index);
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}
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updateCount = 0;
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}
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}
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@ -118,27 +118,20 @@ JNIEXPORT void JNICALL
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Java_sun_nio_ch_DevPollArrayWrapper_register(JNIEnv *env, jobject this,
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jint wfd, jint fd, jint mask)
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{
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struct pollfd a[2];
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unsigned char *pollBytes = (unsigned char *)&a[0];
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unsigned char *pollEnd = pollBytes + sizeof(struct pollfd) * 2;
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struct pollfd a[1];
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int n;
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/* We clear it first, otherwise any entries between poll invocations
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get OR'd together */
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a[0].fd = fd;
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a[0].events = POLLREMOVE;
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a[0].events = mask;
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a[0].revents = 0;
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a[1].fd = fd;
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a[1].events = mask;
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a[1].revents = 0;
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while (pollBytes < pollEnd) {
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int bytesWritten = write(wfd, pollBytes, (int)(pollEnd - pollBytes));
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if (bytesWritten < 0) {
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n = write(wfd, &a[0], sizeof(a));
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if (n != sizeof(a)) {
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if (n < 0) {
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JNU_ThrowIOExceptionWithLastError(env, "Error writing pollfds");
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return;
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} else {
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JNU_ThrowIOException(env, "Unexpected number of bytes written");
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}
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pollBytes += bytesWritten;
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}
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}
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