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Fix CachingHiveMetastore.getPartitionsByNames failing while cache invalidation #12439

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Merged
findepi merged 3 commits into from
May 23, 2022
Merged

Fix CachingHiveMetastore.getPartitionsByNames failing while cache invalidation #12439

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d9b3f94
Add test for concurrent load sharing in EvictableCache
findepi May 20, 2022
4a31b9e
Fix CachingHiveMetastore.getPartitionsByNames failing while cache inv…
findepi May 17, 2022
7942403
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findepi May 20, 2022
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71 changes: 49 additions & 22 deletions lib/trino-collect/src/main/java/io/trino/collect/cache/EvictableCache.java
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Original file line number Diff line number Diff line change
Expand Up @@ -21,8 +21,6 @@
import com.google.common.cache.CacheStats;
import com.google.common.cache.LoadingCache;
import com.google.common.cache.RemovalCause;
import com.google.common.collect.BiMap;
import com.google.common.collect.HashBiMap;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.util.concurrent.ListenableFuture;
Expand All @@ -32,6 +30,8 @@

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
Expand All @@ -41,7 +41,6 @@
import java.util.concurrent.ExecutionException;

import static com.google.common.base.MoreObjects.toStringHelper;
import static com.google.common.base.Preconditions.checkState;
import static com.google.common.base.Verify.verify;
import static java.lang.String.format;
import static java.util.Objects.requireNonNull;
Expand Down Expand Up @@ -144,42 +143,50 @@ public ImmutableMap<K, V> getAll(Iterable<? extends K> keys)
throws ExecutionException
{
List<Token<K>> newTokens = new ArrayList<>();
List<Token<K>> temporaryTokens = new ArrayList<>();
try {
BiMap<K, Token<K>> keyToToken = HashBiMap.create();
Map<K, V> result = new LinkedHashMap<>();
for (K key : keys) {
if (result.containsKey(key)) {
continue;
}
// This is not bulk, but is fast local operation
Token<K> newToken = new Token<>(key);
Token<K> token = tokens.computeIfAbsent(key, ignored -> newToken);
keyToToken.put(key, token);
if (token == newToken) {
newTokens.add(newToken);
Token<K> oldToken = tokens.putIfAbsent(key, newToken);
if (oldToken != null) {
// Token exists but a data may not exist (e.g. due to concurrent eviction)
V value = dataCache.getIfPresent(oldToken);
if (value != null) {
result.put(key, value);
continue;
}
// Old token exists but value wasn't found. This can happen when there is concurrent eviction/invalidation
// or when the value is still being loaded. The new token is not registered in tokens, so won't be used
// by subsequent invocations.
temporaryTokens.add(newToken);
}
newTokens.add(newToken);
}

Map<Token<K>, V> values = dataCache.getAll(keyToToken.values());

BiMap<Token<K>, K> tokenToKey = keyToToken.inverse();
ImmutableMap.Builder<K, V> result = ImmutableMap.builder();
Map<Token<K>, V> values = dataCache.getAll(newTokens);
for (Map.Entry<Token<K>, V> entry : values.entrySet()) {
Token<K> token = entry.getKey();

// While token.getKey() returns equal key, a caller may expect us to maintain key identity, in case equal keys are still distinguishable.
K key = tokenToKey.get(token);
checkState(key != null, "No key found for %s in %s when loading %s", token, tokenToKey, keys);

result.put(key, entry.getValue());
Token<K> newToken = entry.getKey();
result.put(newToken.getKey(), entry.getValue());
}
return result.buildOrThrow();
return ImmutableMap.copyOf(result);
}
catch (Throwable e) {
for (Token<K> token : newTokens) {
// Failed to load and it was our new token persisted in tokens map.
// Failed to load and it was our new token (potentially) persisted in tokens map.
// No cache entry exists for the token (unless concurrent load happened),
// so we need to remove it.
tokens.remove(token.getKey(), token);
}
throw e;
}
finally {
dataCache.invalidateAll(temporaryTokens);
}
}

@Override
Expand Down Expand Up @@ -226,6 +233,16 @@ public void invalidateAll()
tokens.clear();
}

// Not thread safe, test only.
@VisibleForTesting
void clearDataCacheOnly()
{
Map<K, Token<K>> tokensCopy = new HashMap<>(tokens);
dataCache.asMap().clear();
verify(tokens.isEmpty(), "Clearing dataCache should trigger tokens eviction");
tokens.putAll(tokensCopy);
}

@Override
public CacheStats stats()
{
Expand Down Expand Up @@ -406,7 +423,17 @@ public Map<Token<K>, V> loadAll(Iterable<? extends Token<K>> tokens)
for (Token<K> token : tokenList) {
keys.add(token.getKey());
}
Map<? super K, V> values = delegate.loadAll(keys);
Map<? super K, V> values;
try {
values = delegate.loadAll(keys);
}
catch (UnsupportedLoadingOperationException e) {
// Guava uses UnsupportedLoadingOperationException in LoadingCache.loadAll to fall back from bulk loading (without load sharing)
// to loading individual values (with load sharing). EvictableCache implementation does not currently support the fallback mechanism,
// so the individual values would be loaded without load sharing. This would be an unintentional and non-obvious behavioral
// discrepancy between EvictableCache and Guava Caches, so the mechanism is disabled.
throw new UnsupportedOperationException("LoadingCache.getAll() is not supported by EvictableCache when CacheLoader.loadAll is not implemented", e);
}

ImmutableMap.Builder<Token<K>, V> result = ImmutableMap.builder();
for (int i = 0; i < tokenList.size(); i++) {
Expand Down
58 changes: 58 additions & 0 deletions lib/trino-collect/src/test/java/io/trino/collect/cache/TestEvictableCache.java
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@
import com.google.common.base.Strings;
import com.google.common.cache.Cache;
import com.google.common.cache.CacheStats;
import com.google.common.cache.LoadingCache;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import org.gaul.modernizer_maven_annotations.SuppressModernizer;
Expand All @@ -25,15 +26,18 @@
import java.util.ArrayList;
import java.util.List;
import java.util.Set;
import java.util.concurrent.Callable;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;
import java.util.stream.IntStream;

import static com.google.common.base.Preconditions.checkState;
import static com.google.common.collect.ImmutableList.toImmutableList;
import static com.google.common.collect.ImmutableSet.toImmutableSet;
import static io.trino.collect.cache.CacheStatsAssertions.assertCacheStats;
Expand Down Expand Up @@ -275,6 +279,60 @@ private static Integer newInteger(int value)
return newInteger;
}

/**
* Test that the loader is invoked only once for concurrent invocations of {{@link LoadingCache#get(Object, Callable)} with equal keys.
* This is a behavior of Guava Cache as well. While this is necessarily desirable behavior (see
* <a href="https://github.com/trinodb/trino/issues/11067">https://github.com/trinodb/trino/issues/11067</a>),
* the test exists primarily to document current state and support discussion, should the current state change.
*/
@Test(timeOut = TEST_TIMEOUT_MILLIS)
public void testConcurrentGetWithCallableShareLoad()
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@martint martint May 20, 2022

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We should look into jcstress (https://github.com/openjdk/jcstress) for testing concurrency (for later, not as part of this PR).

throws Exception
{
AtomicInteger loads = new AtomicInteger();
AtomicInteger concurrentInvocations = new AtomicInteger();

Cache<Integer, Integer> cache = EvictableCacheBuilder.newBuilder()
.maximumSize(10_000)
.build();

int threads = 2;
int invocationsPerThread = 100;
ExecutorService executor = newFixedThreadPool(threads);
try {
CyclicBarrier barrier = new CyclicBarrier(threads);
List<Future<?>> futures = new ArrayList<>();
for (int i = 0; i < threads; i++) {
futures.add(executor.submit(() -> {
for (int invocation = 0; invocation < invocationsPerThread; invocation++) {
int key = invocation;
barrier.await(10, SECONDS);
int value = cache.get(key, () -> {
loads.incrementAndGet();
int invocations = concurrentInvocations.incrementAndGet();
checkState(invocations == 1, "There should be no concurrent invocations, cache should do load sharing when get() invoked for same key");
Thread.sleep(1);
concurrentInvocations.decrementAndGet();
return -key;
});
assertEquals(value, -invocation);
}
return null;
}));
}

for (Future<?> future : futures) {
future.get(10, SECONDS);
}
assertThat(loads).as("loads")
.hasValueBetween(invocationsPerThread, threads * invocationsPerThread - 1 /* inclusive */);
}
finally {
executor.shutdownNow();
executor.awaitTermination(10, SECONDS);
}
}

/**
* Covers https://github.com/google/guava/issues/1881
*/
Expand Down
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