From 331b50c7cbd8b46b530ee5d870acd64b8ed2f3f5 Mon Sep 17 00:00:00 2001 From: Christos Gkekas Date: Thu, 15 Jul 2021 07:31:34 +0100 Subject: [PATCH] Removes the purge thread in favor of standard ScheduledThreadPoolExecutor APIs The RXSchedulerPurge thread is currently enabled by default and runs every second to call purge() on each executor in the pool. This is causing significant issues for low powered devices (e.g. mobile phones), because it needs to periodically wake up the CPU to perform purging. The RXSchedulerPurge thread could be completely removed in favor of using the standard setRemoveOnCancelPolicy() API on the ScheduledThreadPoolExecutor which became available in Java 7 and offers removal of cancelled tasks at the moment they are cancelled in O(1). --- .../schedulers/SchedulerPoolFactory.java | 99 +------------------ .../rxjava3/schedulers/Schedulers.java | 5 +- .../schedulers/SchedulerPoolFactoryTest.java | 86 ---------------- .../schedulers/ExecutorSchedulerTest.java | 2 +- 4 files changed, 4 insertions(+), 188 deletions(-) diff --git a/src/main/java/io/reactivex/rxjava3/internal/schedulers/SchedulerPoolFactory.java b/src/main/java/io/reactivex/rxjava3/internal/schedulers/SchedulerPoolFactory.java index 043569334c..515c2f2061 100644 --- a/src/main/java/io/reactivex/rxjava3/internal/schedulers/SchedulerPoolFactory.java +++ b/src/main/java/io/reactivex/rxjava3/internal/schedulers/SchedulerPoolFactory.java @@ -31,86 +31,11 @@ private SchedulerPoolFactory() { static final String PURGE_ENABLED_KEY = "rx3.purge-enabled"; - /** - * Indicates the periodic purging of the ScheduledExecutorService is enabled. - */ public static final boolean PURGE_ENABLED; - static final String PURGE_PERIOD_SECONDS_KEY = "rx3.purge-period-seconds"; - - /** - * Indicates the purge period of the ScheduledExecutorServices created by create(). - */ - public static final int PURGE_PERIOD_SECONDS; - - static final AtomicReference PURGE_THREAD = - new AtomicReference<>(); - - // Upcast to the Map interface here to avoid 8.x compatibility issues. - // See http://stackoverflow.com/a/32955708/61158 - static final Map POOLS = - new ConcurrentHashMap<>(); - - /** - * Starts the purge thread if not already started. - */ - public static void start() { - tryStart(PURGE_ENABLED); - } - - static void tryStart(boolean purgeEnabled) { - if (purgeEnabled) { - for (;;) { - ScheduledExecutorService curr = PURGE_THREAD.get(); - if (curr != null) { - return; - } - ScheduledExecutorService next = Executors.newScheduledThreadPool(1, new RxThreadFactory("RxSchedulerPurge")); - if (PURGE_THREAD.compareAndSet(curr, next)) { - - next.scheduleAtFixedRate(new ScheduledTask(), PURGE_PERIOD_SECONDS, PURGE_PERIOD_SECONDS, TimeUnit.SECONDS); - - return; - } else { - next.shutdownNow(); - } - } - } - } - - /** - * Stops the purge thread. - */ - public static void shutdown() { - ScheduledExecutorService exec = PURGE_THREAD.getAndSet(null); - if (exec != null) { - exec.shutdownNow(); - } - POOLS.clear(); - } - static { SystemPropertyAccessor propertyAccessor = new SystemPropertyAccessor(); PURGE_ENABLED = getBooleanProperty(true, PURGE_ENABLED_KEY, true, true, propertyAccessor); - PURGE_PERIOD_SECONDS = getIntProperty(PURGE_ENABLED, PURGE_PERIOD_SECONDS_KEY, 1, 1, propertyAccessor); - - start(); - } - - static int getIntProperty(boolean enabled, String key, int defaultNotFound, int defaultNotEnabled, Function propertyAccessor) { - if (enabled) { - try { - String value = propertyAccessor.apply(key); - if (value == null) { - return defaultNotFound; - } - return Integer.parseInt(value); - } catch (Throwable ex) { - Exceptions.throwIfFatal(ex); - return defaultNotFound; - } - } - return defaultNotEnabled; } static boolean getBooleanProperty(boolean enabled, String key, boolean defaultNotFound, boolean defaultNotEnabled, Function propertyAccessor) { @@ -142,28 +67,8 @@ public String apply(String t) { * @return the ScheduledExecutorService */ public static ScheduledExecutorService create(ThreadFactory factory) { - final ScheduledExecutorService exec = Executors.newScheduledThreadPool(1, factory); - tryPutIntoPool(PURGE_ENABLED, exec); + final ScheduledThreadPoolExecutor exec = new ScheduledThreadPoolExecutor(1, factory); + exec.setRemoveOnCancelPolicy(PURGE_ENABLED); return exec; } - - static void tryPutIntoPool(boolean purgeEnabled, ScheduledExecutorService exec) { - if (purgeEnabled && exec instanceof ScheduledThreadPoolExecutor) { - ScheduledThreadPoolExecutor e = (ScheduledThreadPoolExecutor) exec; - POOLS.put(e, exec); - } - } - - static final class ScheduledTask implements Runnable { - @Override - public void run() { - for (ScheduledThreadPoolExecutor e : new ArrayList<>(POOLS.keySet())) { - if (e.isShutdown()) { - POOLS.remove(e); - } else { - e.purge(); - } - } - } - } } diff --git a/src/main/java/io/reactivex/rxjava3/schedulers/Schedulers.java b/src/main/java/io/reactivex/rxjava3/schedulers/Schedulers.java index 0c0ecbdbe5..f5dbe6ce7c 100644 --- a/src/main/java/io/reactivex/rxjava3/schedulers/Schedulers.java +++ b/src/main/java/io/reactivex/rxjava3/schedulers/Schedulers.java @@ -38,8 +38,7 @@ *
  • {@code rx3.computation-priority} (int): sets the thread priority of the {@link #computation()} {@code Scheduler}, default is {@link Thread#NORM_PRIORITY}
    • *
  • {@code rx3.newthread-priority} (int): sets the thread priority of the {@link #newThread()} {@code Scheduler}, default is {@link Thread#NORM_PRIORITY}
    • *
  • {@code rx3.single-priority} (int): sets the thread priority of the {@link #single()} {@code Scheduler}, default is {@link Thread#NORM_PRIORITY}
    • - *
  • {@code rx3.purge-enabled} (boolean): enables periodic purging of all {@code Scheduler}'s backing thread pools, default is {@code false}
    • - *
  • {@code rx3.purge-period-seconds} (int): specifies the periodic purge interval of all {@code Scheduler}'s backing thread pools, default is 1 second
    • + *
  • {@code rx3.purge-enabled} (boolean): enables purging of all {@code Scheduler}'s backing thread pools, default is {@code true}
    • *
  • {@code rx3.scheduler.use-nanotime} (boolean): {@code true} instructs {@code Scheduler} to use {@link System#nanoTime()} for {@link Scheduler#now(TimeUnit)}, * instead of default {@link System#currentTimeMillis()} ({@code false})
    • * @@ -556,7 +555,6 @@ public static void shutdown() { newThread().shutdown(); single().shutdown(); trampoline().shutdown(); - SchedulerPoolFactory.shutdown(); } /** @@ -569,7 +567,6 @@ public static void start() { newThread().start(); single().start(); trampoline().start(); - SchedulerPoolFactory.start(); } static final class IOTask implements Supplier { diff --git a/src/test/java/io/reactivex/rxjava3/internal/schedulers/SchedulerPoolFactoryTest.java b/src/test/java/io/reactivex/rxjava3/internal/schedulers/SchedulerPoolFactoryTest.java index dd5667ffbb..5d93dabc09 100644 --- a/src/test/java/io/reactivex/rxjava3/internal/schedulers/SchedulerPoolFactoryTest.java +++ b/src/test/java/io/reactivex/rxjava3/internal/schedulers/SchedulerPoolFactoryTest.java @@ -30,50 +30,6 @@ public void utilityClass() { TestHelper.checkUtilityClass(SchedulerPoolFactory.class); } - @Test - public void multiStartStop() { - SchedulerPoolFactory.shutdown(); - - SchedulerPoolFactory.shutdown(); - - SchedulerPoolFactory.tryStart(false); - - assertNull(SchedulerPoolFactory.PURGE_THREAD.get()); - - SchedulerPoolFactory.start(); - - // restart schedulers - Schedulers.shutdown(); - - Schedulers.start(); - } - - @Test - public void startRace() throws InterruptedException { - try { - for (int i = 0; i < TestHelper.RACE_DEFAULT_LOOPS; i++) { - SchedulerPoolFactory.shutdown(); - - Runnable r1 = new Runnable() { - @Override - public void run() { - SchedulerPoolFactory.start(); - } - }; - - TestHelper.race(r1, r1); - } - - } finally { - // restart schedulers - Schedulers.shutdown(); - - Thread.sleep(200); - - Schedulers.start(); - } - } - @Test public void boolPropertiesDisabledReturnsDefaultDisabled() throws Throwable { assertTrue(SchedulerPoolFactory.getBooleanProperty(false, "key", false, true, failingPropertiesAccessor)); @@ -98,30 +54,6 @@ public void boolPropertiesReturnsValue() throws Throwable { assertFalse(SchedulerPoolFactory.getBooleanProperty(true, "false", false, true, Functions.identity())); } - @Test - public void intPropertiesDisabledReturnsDefaultDisabled() throws Throwable { - assertEquals(-1, SchedulerPoolFactory.getIntProperty(false, "key", 0, -1, failingPropertiesAccessor)); - assertEquals(-1, SchedulerPoolFactory.getIntProperty(false, "key", 1, -1, failingPropertiesAccessor)); - } - - @Test - public void intPropertiesEnabledMissingReturnsDefaultMissing() throws Throwable { - assertEquals(-1, SchedulerPoolFactory.getIntProperty(true, "key", -1, 0, missingPropertiesAccessor)); - assertEquals(-1, SchedulerPoolFactory.getIntProperty(true, "key", -1, 1, missingPropertiesAccessor)); - } - - @Test - public void intPropertiesFailureReturnsDefaultMissing() throws Throwable { - assertEquals(-1, SchedulerPoolFactory.getIntProperty(true, "key", -1, 0, failingPropertiesAccessor)); - assertEquals(-1, SchedulerPoolFactory.getIntProperty(true, "key", -1, 1, failingPropertiesAccessor)); - } - - @Test - public void intPropertiesReturnsValue() throws Throwable { - assertEquals(1, SchedulerPoolFactory.getIntProperty(true, "1", 0, 4, Functions.identity())); - assertEquals(2, SchedulerPoolFactory.getIntProperty(true, "2", 3, 5, Functions.identity())); - } - static final Function failingPropertiesAccessor = new Function() { @Override public String apply(String v) throws Throwable { @@ -135,22 +67,4 @@ public String apply(String v) throws Throwable { return null; } }; - - @Test - public void putIntoPoolNoPurge() { - int s = SchedulerPoolFactory.POOLS.size(); - - SchedulerPoolFactory.tryPutIntoPool(false, null); - - assertEquals(s, SchedulerPoolFactory.POOLS.size()); - } - - @Test - public void putIntoPoolNonThreadPool() { - int s = SchedulerPoolFactory.POOLS.size(); - - SchedulerPoolFactory.tryPutIntoPool(true, null); - - assertEquals(s, SchedulerPoolFactory.POOLS.size()); - } } diff --git a/src/test/java/io/reactivex/rxjava3/schedulers/ExecutorSchedulerTest.java b/src/test/java/io/reactivex/rxjava3/schedulers/ExecutorSchedulerTest.java index c4ba94189c..bb3e759884 100644 --- a/src/test/java/io/reactivex/rxjava3/schedulers/ExecutorSchedulerTest.java +++ b/src/test/java/io/reactivex/rxjava3/schedulers/ExecutorSchedulerTest.java @@ -93,7 +93,7 @@ public void run() { System.out.println("Wait before second GC"); System.out.println("JDK 6 purge is N log N because it removes and shifts one by one"); - int t = (int)(n * Math.log(n) / 100) + SchedulerPoolFactory.PURGE_PERIOD_SECONDS * 1000; + int t = (int)(n * Math.log(n) / 100) + 1000; int sleepStep = 100; while (t > 0) { System.out.printf(" >> Waiting for purge: %.2f s remaining%n", t / 1000d);