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Posted to gitbox@hive.apache.org by GitBox <gi...@apache.org> on 2021/05/24 15:13:10 UTC
[GitHub] [hive] belugabehr opened a new pull request #2312: HIVE-25157: Clean up QueryResultsCache Code
belugabehr opened a new pull request #2312:
URL: https://github.com/apache/hive/pull/2312
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[GitHub] [hive] belugabehr commented on a change in pull request #2312: HIVE-25157: Clean up QueryResultsCache Code
Posted by GitBox <gi...@apache.org>.
belugabehr commented on a change in pull request #2312:
URL: https://github.com/apache/hive/pull/2312#discussion_r639709076
##########
File path: ql/src/java/org/apache/hadoop/hive/ql/cache/results/QueryResultsCache.java
##########
@@ -814,37 +784,11 @@ private boolean clearSpaceForCacheEntry(CacheEntry entry, long size) {
}
}
- LOG.info("Could not free enough space for cache entry for query: [{}] withe size {}",
+ LOG.info("Could not free enough space for cache entry for query: [{}] with size {}",
entry.getQueryText(), size);
return false;
}
- private static void addToEntryMap(Map<String, Set<CacheEntry>> entryMap,
- String key, CacheEntry entry) {
- Set<CacheEntry> entriesForKey = entryMap.get(key);
- if (entriesForKey == null) {
- entriesForKey = new HashSet<CacheEntry>();
- entryMap.put(key, entriesForKey);
- }
- entriesForKey.add(entry);
- }
-
- private static boolean removeFromEntryMap(Map<String, Set<CacheEntry>> entryMap,
- String key, CacheEntry entry) {
- Set<CacheEntry> entries = entryMap.get(key);
- if (entries == null) {
- return false;
- }
- boolean deleted = entries.remove(entry);
- if (!deleted) {
- return false;
- }
- if (entries.isEmpty()) {
- entryMap.remove(key);
- }
- return true;
- }
-
Review comment:
Using Guava `Multimap` makes this dead code
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[GitHub] [hive] belugabehr commented on a change in pull request #2312: HIVE-25157: Clean up QueryResultsCache Code
Posted by GitBox <gi...@apache.org>.
belugabehr commented on a change in pull request #2312:
URL: https://github.com/apache/hive/pull/2312#discussion_r639711891
##########
File path: ql/src/java/org/apache/hadoop/hive/ql/cache/results/QueryResultsCache.java
##########
@@ -319,9 +312,8 @@ public boolean waitForValidStatus() {
// Status has not changed, continue waiting.
break;
}
-
synchronized (this) {
- this.wait(timeout);
+ this.wait();
Review comment:
This thread is waiting on the state change. Adding a timeout doesn't cause the loop to exit, instead the thread will just loop and see that there was no change and `wait` again. This timeout only adds churn.
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[GitHub] [hive] belugabehr commented on a change in pull request #2312: HIVE-25157: Clean up QueryResultsCache Code
Posted by GitBox <gi...@apache.org>.
belugabehr commented on a change in pull request #2312:
URL: https://github.com/apache/hive/pull/2312#discussion_r639715093
##########
File path: ql/src/java/org/apache/hadoop/hive/ql/cache/results/QueryResultsCache.java
##########
@@ -726,35 +709,24 @@ private boolean entryMatches(LookupInfo lookupInfo, CacheEntry entry, Set<CacheE
public void removeEntry(CacheEntry entry) {
entry.invalidate();
- rwLock.writeLock().lock();
+ cacheWriteLock.lock();
try {
- removeFromLookup(entry);
+ String queryString = entry.getQueryText();
+ if (!queryMap.remove(queryString, entry)) {
+ LOG.warn("Attempted to remove entry but it was not in the cache: {}", entry);
+ }
+
+ // Remove this entry from the table usage mappings.
+ entry.getTableNames().forEach(tableName -> tableToEntryMap.remove(tableName, entry));
+
Review comment:
Moved out from having its own method
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[GitHub] [hive] klcopp commented on pull request #2312: HIVE-25157: Clean up QueryResultsCache Code
Posted by GitBox <gi...@apache.org>.
klcopp commented on pull request #2312:
URL: https://github.com/apache/hive/pull/2312#issuecomment-851459610
@belugabehr I don't in the next couple weeks, sorry :/
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[GitHub] [hive] belugabehr commented on a change in pull request #2312: HIVE-25157: Clean up QueryResultsCache Code
Posted by GitBox <gi...@apache.org>.
belugabehr commented on a change in pull request #2312:
URL: https://github.com/apache/hive/pull/2312#discussion_r639710071
##########
File path: ql/src/java/org/apache/hadoop/hive/ql/cache/results/QueryResultsCache.java
##########
@@ -726,35 +709,24 @@ private boolean entryMatches(LookupInfo lookupInfo, CacheEntry entry, Set<CacheE
public void removeEntry(CacheEntry entry) {
entry.invalidate();
- rwLock.writeLock().lock();
+ cacheWriteLock.lock();
try {
- removeFromLookup(entry);
+ String queryString = entry.getQueryText();
+ if (!queryMap.remove(queryString, entry)) {
+ LOG.warn("Attempted to remove entry but it was not in the cache: {}", entry);
+ }
+
+ // Remove this entry from the table usage mappings.
+ entry.getTableNames().forEach(tableName -> tableToEntryMap.remove(tableName, entry));
+
lru.remove(entry);
// Should the cache size be updated here, or after the result data has actually been deleted?
cacheSize -= entry.size;
} finally {
- rwLock.writeLock().unlock();
+ cacheWriteLock.unlock();
}
}
- private void removeFromLookup(CacheEntry entry) {
- String queryString = entry.getQueryText();
- if (!removeFromEntryMap(queryMap, queryString, entry)) {
- LOG.warn("Attempted to remove entry but it was not in the cache: {}", entry);
- }
-
- // Remove this entry from the table usage mappings.
- entry.getTableNames()
- .forEach(tableName -> removeFromEntryMap(tableToEntryMap, tableName, entry));
- }
-
- private void calculateEntrySize(CacheEntry entry, FetchWork fetchWork) throws IOException {
- Path queryResultsPath = fetchWork.getTblDir();
- FileSystem resultsFs = queryResultsPath.getFileSystem(conf);
- ContentSummary cs = resultsFs.getContentSummary(queryResultsPath);
- entry.size = cs.getLength();
- }
-
Review comment:
Unused code.
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[GitHub] [hive] belugabehr commented on a change in pull request #2312: HIVE-25157: Clean up QueryResultsCache Code
Posted by GitBox <gi...@apache.org>.
belugabehr commented on a change in pull request #2312:
URL: https://github.com/apache/hive/pull/2312#discussion_r639708841
##########
File path: ql/src/java/org/apache/hadoop/hive/ql/cache/results/QueryResultsCache.java
##########
@@ -885,8 +824,6 @@ public void run() {
private static void cleanupEntry(final CacheEntry entry) {
Preconditions.checkState(entry.getStatus() == CacheEntryStatus.INVALID);
- final HiveConf conf = getInstance().conf;
-
Review comment:
Unused code.
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[GitHub] [hive] belugabehr commented on a change in pull request #2312: HIVE-25157: Clean up QueryResultsCache Code
Posted by GitBox <gi...@apache.org>.
belugabehr commented on a change in pull request #2312:
URL: https://github.com/apache/hive/pull/2312#discussion_r639714420
##########
File path: ql/src/java/org/apache/hadoop/hive/ql/cache/results/QueryResultsCache.java
##########
@@ -601,66 +591,59 @@ public boolean setEntryValid(CacheEntry cacheEntry, FetchWork fetchWork) {
}
public void clear() {
- Lock writeLock = rwLock.writeLock();
+ cacheWriteLock.lock();
try {
- writeLock.lock();
LOG.info("Clearing the results cache");
- CacheEntry[] allEntries = null;
- synchronized (lru) {
- allEntries = lru.keySet().toArray(EMPTY_CACHEENTRY_ARRAY);
- }
- for (CacheEntry entry : allEntries) {
Review comment:
The `cacheWrite` lock is held here so no need to synchronize on `lru`
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[GitHub] [hive] belugabehr commented on a change in pull request #2312: HIVE-25157: Clean up QueryResultsCache Code
Posted by GitBox <gi...@apache.org>.
belugabehr commented on a change in pull request #2312:
URL: https://github.com/apache/hive/pull/2312#discussion_r639711031
##########
File path: ql/src/java/org/apache/hadoop/hive/ql/cache/results/QueryResultsCache.java
##########
@@ -260,6 +252,7 @@ private CacheEntryStatus setStatus(CacheEntryStatus newStatus) {
synchronized (this) {
CacheEntryStatus oldStatus = status;
status = newStatus;
+ this.notifyAll();
return oldStatus;
Review comment:
Notify waiting threads when the status changes. This is the correct way to do this instead of putting `notifyAll` in a bunch of different places.
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[GitHub] [hive] github-actions[bot] closed pull request #2312: HIVE-25157: Clean up QueryResultsCache Code
Posted by GitBox <gi...@apache.org>.
github-actions[bot] closed pull request #2312:
URL: https://github.com/apache/hive/pull/2312
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[GitHub] [hive] belugabehr commented on a change in pull request #2312: HIVE-25157: Clean up QueryResultsCache Code
Posted by GitBox <gi...@apache.org>.
belugabehr commented on a change in pull request #2312:
URL: https://github.com/apache/hive/pull/2312#discussion_r639710520
##########
File path: ql/src/java/org/apache/hadoop/hive/ql/cache/results/QueryResultsCache.java
##########
@@ -338,15 +330,17 @@ public boolean waitForValidStatus() {
}
// Allow lookup by query string
- private final Map<String, Set<CacheEntry>> queryMap = new HashMap<String, Set<CacheEntry>>();
+ @GuardedBy("cacheLock")
+ private final Multimap<String, CacheEntry> queryMap = HashMultimap.create();
// LRU. Could also implement LRU as a doubly linked list if CacheEntry keeps its node.
// Use synchronized map since even read actions cause the lru to get updated.
- private final Map<CacheEntry, CacheEntry> lru = Collections.synchronizedMap(
- new LinkedHashMap<CacheEntry, CacheEntry>(INITIAL_LRU_SIZE, LRU_LOAD_FACTOR, true));
+ private final Set<CacheEntry> lru =
+ Collections.synchronizedSet(Collections.newSetFromMap(new LinkedHashMap<>(16, 0.75f, true)));
Review comment:
Use `Set` instead of Map with the same key/value
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[GitHub] [hive] belugabehr commented on pull request #2312: HIVE-25157: Clean up QueryResultsCache Code
Posted by GitBox <gi...@apache.org>.
belugabehr commented on pull request #2312:
URL: https://github.com/apache/hive/pull/2312#issuecomment-849271893
@klcopp @miklosgergely If you have time. :)
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[GitHub] [hive] belugabehr closed pull request #2312: HIVE-25157: Clean up QueryResultsCache Code
Posted by GitBox <gi...@apache.org>.
belugabehr closed pull request #2312:
URL: https://github.com/apache/hive/pull/2312
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[GitHub] [hive] belugabehr closed pull request #2312: HIVE-25157: Clean up QueryResultsCache Code
Posted by GitBox <gi...@apache.org>.
belugabehr closed pull request #2312:
URL: https://github.com/apache/hive/pull/2312
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[GitHub] [hive] belugabehr commented on a change in pull request #2312: HIVE-25157: Clean up QueryResultsCache Code
Posted by GitBox <gi...@apache.org>.
belugabehr commented on a change in pull request #2312:
URL: https://github.com/apache/hive/pull/2312#discussion_r639713660
##########
File path: ql/src/java/org/apache/hadoop/hive/ql/cache/results/QueryResultsCache.java
##########
@@ -493,20 +491,17 @@ public CacheEntry addToCache(QueryInfo queryInfo, ValidTxnWriteIdList txnWriteId
addedEntry.queryInfo = queryInfo;
addedEntry.txnWriteIdList = txnWriteIdList;
- Lock writeLock = rwLock.writeLock();
+ cacheWriteLock.lock();
try {
- writeLock.lock();
-
Review comment:
Move locks outside the try block as is the official Java Trails way.
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[GitHub] [hive] belugabehr commented on a change in pull request #2312: HIVE-25157: Clean up QueryResultsCache Code
Posted by GitBox <gi...@apache.org>.
belugabehr commented on a change in pull request #2312:
URL: https://github.com/apache/hive/pull/2312#discussion_r639715427
##########
File path: ql/src/java/org/apache/hadoop/hive/ql/cache/results/QueryResultsCache.java
##########
@@ -860,15 +804,10 @@ public static void cleanupInstance() {
}
}
- private static ScheduledExecutorService invalidationExecutor = null;
- private static ExecutorService deletionExecutor = null;
-
- static {
- ThreadFactory threadFactory =
- new ThreadFactoryBuilder().setDaemon(true).setNameFormat("QueryResultsCache %d").build();
- invalidationExecutor = Executors.newSingleThreadScheduledExecutor(threadFactory);
- deletionExecutor = Executors.newSingleThreadExecutor(threadFactory);
- }
+ private static ScheduledExecutorService invalidationExecutor = Executors.newSingleThreadScheduledExecutor(
+ new ThreadFactoryBuilder().setDaemon(true).setNameFormat("QueryCacheInvalidator %d").build());
+ private static ExecutorService deletionExecutor = Executors.newSingleThreadScheduledExecutor(
+ new ThreadFactoryBuilder().setDaemon(true).setNameFormat("QueryCacheDeletor %d").build());
Review comment:
Re-factor and give each pool its own name.
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[GitHub] [hive] github-actions[bot] commented on pull request #2312: HIVE-25157: Clean up QueryResultsCache Code
Posted by GitBox <gi...@apache.org>.
github-actions[bot] commented on pull request #2312:
URL: https://github.com/apache/hive/pull/2312#issuecomment-890260563
This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.
Feel free to reach out on the dev@hive.apache.org list if the patch is in need of reviews.
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[GitHub] [hive] belugabehr commented on a change in pull request #2312: HIVE-25157: Clean up QueryResultsCache Code
Posted by GitBox <gi...@apache.org>.
belugabehr commented on a change in pull request #2312:
URL: https://github.com/apache/hive/pull/2312#discussion_r639713247
##########
File path: ql/src/java/org/apache/hadoop/hive/ql/cache/results/QueryResultsCache.java
##########
@@ -416,58 +412,60 @@ public Path getCacheDirPath() {
/**
* Check if the cache contains an entry for the requested LookupInfo.
+ *
* @param request
- * @return The cached result if there is a match in the cache, or null if no match is found.
+ * @return The cached result if there is a match in the cache, or null if no
+ * match is found.
+ * @throws NullPointerException if request is {@code null}
*/
- public CacheEntry lookup(LookupInfo request) {
- CacheEntry result = null;
+ public CacheEntry lookup(final LookupInfo request) {
+ Objects.requireNonNull(request);
- LOG.debug("QueryResultsCache lookup for query: {}", request.queryText);
+ LOG.debug("Cache lookup for query: {}", request.queryText);
+ CacheEntry result = null;
boolean foundPending = false;
- // Cannot entries while we currently hold read lock, so keep track of them to delete later.
- Set<CacheEntry> entriesToRemove = new HashSet<CacheEntry>();
- Lock readLock = rwLock.readLock();
+ // Cannot modify entries while we currently hold read lock, so keep track of
+ // them to delete later.
+ Set<CacheEntry> entriesToRemove = new HashSet<>();
+ cacheReadLock.lock();
try {
- // Note: ReentrantReadWriteLock deos not allow upgrading a read lock to a write lock.
+ // Note: ReentrantReadWriteLock does not allow upgrading a read lock to a write lock.
// Care must be taken while under read lock, to make sure we do not perform any actions
// which attempt to take a write lock.
- readLock.lock();
- Set<CacheEntry> candidates = queryMap.get(request.queryText);
- if (candidates != null) {
- CacheEntry pendingResult = null;
- for (CacheEntry candidate : candidates) {
- if (entryMatches(request, candidate, entriesToRemove)) {
- CacheEntryStatus entryStatus = candidate.status;
- if (entryStatus == CacheEntryStatus.VALID) {
- result = candidate;
- break;
- } else if (entryStatus == CacheEntryStatus.PENDING && pendingResult == null) {
- pendingResult = candidate;
- }
+ Collection<CacheEntry> candidates = queryMap.get(request.queryText);
+ // Try to find valid entry, but settle for pending entry if that is all
+ // there is available
+ for (CacheEntry candidate : candidates) {
+ if (entryMatches(request, candidate, entriesToRemove)) {
+ CacheEntryStatus entryStatus = candidate.status;
+ if (entryStatus == CacheEntryStatus.VALID) {
+ result = candidate;
+ break;
+ }
+ if (entryStatus == CacheEntryStatus.PENDING) {
+ // Only accept first pending result
+ result = (result == null) ? candidate : result;
Review comment:
`queryMap` is now a Guava `Multimap` and therefore does not return null values (it returns empty `Collection`). Otherwise just simplifying the code.
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[GitHub] [hive] belugabehr commented on a change in pull request #2312: HIVE-25157: Clean up QueryResultsCache Code
Posted by GitBox <gi...@apache.org>.
belugabehr commented on a change in pull request #2312:
URL: https://github.com/apache/hive/pull/2312#discussion_r639712397
##########
File path: ql/src/java/org/apache/hadoop/hive/ql/cache/results/QueryResultsCache.java
##########
@@ -355,7 +349,9 @@ public boolean waitForValidStatus() {
private long maxCacheSize;
private long maxEntrySize;
private long maxEntryLifetime;
- private ReadWriteLock rwLock = new ReentrantReadWriteLock();
+ private final ReadWriteLock cacheLock = new ReentrantReadWriteLock();
+ private final Lock cacheReadLock = cacheLock.readLock();
+ private final Lock cacheWriteLock = cacheLock.writeLock();
Review comment:
Breakout the `cacheLock` into its parts. Simplifies code that relies on them.
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[GitHub] [hive] belugabehr commented on a change in pull request #2312: HIVE-25157: Clean up QueryResultsCache Code
Posted by GitBox <gi...@apache.org>.
belugabehr commented on a change in pull request #2312:
URL: https://github.com/apache/hive/pull/2312#discussion_r639709847
##########
File path: ql/src/java/org/apache/hadoop/hive/ql/cache/results/QueryResultsCache.java
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@@ -783,13 +755,11 @@ private boolean hasSpaceForCacheEntry(CacheEntry entry, long size) {
private CacheEntry findEntryToRemove() {
// Entries should be in LRU order in the keyset iterator.
- Set<CacheEntry> entries = lru.keySet();
synchronized (lru) {
- for (CacheEntry removalCandidate : entries) {
- if (removalCandidate.getStatus() != CacheEntryStatus.VALID) {
- continue;
+ for (CacheEntry removalCandidate : lru) {
+ if (removalCandidate.getStatus() == CacheEntryStatus.VALID) {
+ return removalCandidate;
}
- return removalCandidate;
Review comment:
Grab the `keySet` _inside_ of the synchronized block to avoid ConcurrentModification. Remove use of 'continue' keyword.
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