所以我们正在使用Guava v18。 我们对这个内容进行了很多讨论：
"catalina-exec-ajp2" daemon prio=10 tid=0x00007fb45c001800 nid=0x18aa waiting on condition [0x00007fb435151000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x000000075ff0cfe8> (a com.google.common.util.concurrent.AbstractFuture$Sync)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:834)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedInterruptibly(AbstractQueuedSynchronizer.java:994)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireSharedInterruptibly(AbstractQueuedSynchronizer.java:1303)
at com.google.common.util.concurrent.AbstractFuture$Sync.get(AbstractFuture.java:285)
at com.google.common.util.concurrent.AbstractFuture.get(AbstractFuture.java:116)
at com.google.common.util.concurrent.Uninterruptibles.getUninterruptibly(Uninterruptibles.java:137)
at com.google.common.cache.LocalCache$LoadingValueReference.waitForValue(LocalCache.java:3557)
at com.google.common.cache.LocalCache$Segment.waitForLoadingValue(LocalCache.java:2302)
at com.google.common.cache.LocalCache$Segment.get(LocalCache.java:2191)
at com.google.common.cache.LocalCache.get(LocalCache.java:3937)
at com.google.common.cache.LocalCache.getOrLoad(LocalCache.java:3941)
at com.google.common.cache.LocalCache$LocalLoadingCache.get(LocalCache.java:4824)
at com.google.common.cache.LocalCache$LocalLoadingCache.getUnchecked(LocalCache.java:4830)
at com.xxx.yyy.repository.cache.acl.guava.GuavaCacheWrapper.get(GuavaCacheWrapper.java:21)
at com.xxx.yyy.repository.cache.CachedCpaRepository.findAll(CachedCpaRepository.java:32)
我们的番石榴配置是：
@SuppressWarnings("unchecked")
@Override
protected <K, R> CacheWrapper<K, R> newCacheConfiguration(Fetcher fetcher, String cacheName, int maxElementsInMemory,
int timeToIdleSeconds, int timeToLiveSeconds)
{
Cache existingCache = manager.getCache(cacheName);
CacheWrapper<K, R> cache;
if(null == existingCache)
{
cache = new GuavaCacheWrapper<>(CacheBuilder.newBuilder()
.maximumSize(maxElementsInMemory)
.expireAfterAccess(timeToIdleSeconds, SECONDS)
.refreshAfterWrite(timeToLiveSeconds, SECONDS)
.recordStats()
.build( CacheLoader.asyncReloading(fetcher.getAs(CacheLoader.class), executors)));
manager.addCache(cacheName, cache);
}
else
{
cache = (CacheWrapper<K, R>) ((GuavaCache) existingCache).getNativaGuavaCache();
}
return cache;
}
我对我能检查什么产生问题感到有点无能为力。你能建议我检查一下吗？
答案 0 :(得分：1)
如果你有LoadingCache的阻塞，这意味着你正在从多个线程加载相同密钥的值：第一个线程实际加载该值，下一个线程等待该加载完成
也许您拥有少量密钥并处理该值是一项代价高昂的操作？您可以记录您尝试加载的密钥以及加载的持续时间。
<强>更新
执行实际加载的线程是调用CacheLoader的线程，但是找不到与线程转储中的哪个等待线程相对应的线程（如果有多个线程加载）。
我创建了一个测试来重现这种情况：
public class ExpensiveCache {
private final LoadingCache<String, String> cache = CacheBuilder.newBuilder().build(new ExpensiveCacheLoader());
public static void main(String... args) {
new ExpensiveCache().run();
}
private void run() {
// Start 2 threads concurrently accessing the same key in the cache
for (int i = 0; i < 2; i++) {
new Thread(() -> cache.getUnchecked("key")).start();
}
}
private static class ExpensiveCacheLoader extends CacheLoader<String, String> {
@Override
public String load(String key) throws Exception {
// Make the computation "expensive" by sleeping for 60s
Thread.sleep(60_000);
return key;
}
}
}
你确实无法在线程转储中的任何其他地方找到条件的id：
"Thread-2" #12 prio=5 os_prio=31 tid=0x00007fbb6384e000 nid=0x5703 waiting on condition [0x00000001291c5000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x000000076b183208> (a com.google.common.util.concurrent.AbstractFuture$Sync)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedInterruptibly(AbstractQueuedSynchronizer.java:997)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireSharedInterruptibly(AbstractQueuedSynchronizer.java:1304)
at com.google.common.util.concurrent.AbstractFuture$Sync.get(AbstractFuture.java:285)
at com.google.common.util.concurrent.AbstractFuture.get(AbstractFuture.java:116)
at com.google.common.util.concurrent.Uninterruptibles.getUninterruptibly(Uninterruptibles.java:137)
at com.google.common.cache.LocalCache$LoadingValueReference.waitForValue(LocalCache.java:3557)
at com.google.common.cache.LocalCache$Segment.waitForLoadingValue(LocalCache.java:2302)
at com.google.common.cache.LocalCache$Segment.lockedGetOrLoad(LocalCache.java:2289)
at com.google.common.cache.LocalCache$Segment.get(LocalCache.java:2197)
at com.google.common.cache.LocalCache.get(LocalCache.java:3937)
at com.google.common.cache.LocalCache.getOrLoad(LocalCache.java:3941)
at com.google.common.cache.LocalCache$LocalLoadingCache.get(LocalCache.java:4824)
at com.google.common.cache.LocalCache$LocalLoadingCache.getUnchecked(LocalCache.java:4830)
at io.github.fpavageau.ExpensiveCache.lambda$run$0(ExpensiveCache.java:16)
at io.github.fpavageau.ExpensiveCache$$Lambda$1/1108411398.run(Unknown Source)
at java.lang.Thread.run(Thread.java:745)
"Thread-1" #11 prio=5 os_prio=31 tid=0x00007fbb6384d000 nid=0x5503 waiting on condition [0x00000001290c2000]
java.lang.Thread.State: TIMED_WAITING (sleeping)
at java.lang.Thread.sleep(Native Method)
at io.github.fpavageau.ExpensiveCache$ExpensiveCacheLoader.load(ExpensiveCache.java:23)
at io.github.fpavageau.ExpensiveCache$ExpensiveCacheLoader.load(ExpensiveCache.java:20)
at com.google.common.cache.LocalCache$LoadingValueReference.loadFuture(LocalCache.java:3527)
at com.google.common.cache.LocalCache$Segment.loadSync(LocalCache.java:2319)
at com.google.common.cache.LocalCache$Segment.lockedGetOrLoad(LocalCache.java:2282)
- locked <0x000000076b199a50> (a com.google.common.cache.LocalCache$StrongEntry)
at com.google.common.cache.LocalCache$Segment.get(LocalCache.java:2197)
at com.google.common.cache.LocalCache.get(LocalCache.java:3937)
at com.google.common.cache.LocalCache.getOrLoad(LocalCache.java:3941)
at com.google.common.cache.LocalCache$LocalLoadingCache.get(LocalCache.java:4824)
at com.google.common.cache.LocalCache$LocalLoadingCache.getUnchecked(LocalCache.java:4830)
at io.github.fpavageau.ExpensiveCache.lambda$run$0(ExpensiveCache.java:16)
at io.github.fpavageau.ExpensiveCache$$Lambda$1/1108411398.run(Unknown Source)
at java.lang.Thread.run(Thread.java:745)