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HDDS-10206. Expose jmx metrics for snapshot cache size on the ozone m…
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…anager. (apache#6138)

(cherry picked from commit 301664e)
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@ceekay47 @xichen01
ceekay47 authored and xichen01 committed Jul 17, 2024
1 parent 3fada4b commit 6d0dffe
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Showing 5 changed files with 65 additions and 5 deletions.
13 changes: 13 additions & 0 deletions hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/OMMetrics.java
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Expand Up @@ -26,6 +26,7 @@
import org.apache.hadoop.metrics2.annotation.Metrics;
import org.apache.hadoop.metrics2.lib.DefaultMetricsSystem;
import org.apache.hadoop.metrics2.lib.MutableCounterLong;
import org.apache.hadoop.metrics2.lib.MutableGaugeInt;

/**
* This class is for maintaining Ozone Manager statistics.
Expand Down Expand Up @@ -77,6 +78,7 @@ public class OMMetrics implements OmMetadataReaderMetrics {
private @Metric MutableCounterLong numSnapshotPurges;
private @Metric MutableCounterLong numSnapshotSetProperties;

private @Metric MutableGaugeInt numSnapshotCacheSize;
private @Metric MutableCounterLong numGetFileStatus;
private @Metric MutableCounterLong numCreateDirectory;
private @Metric MutableCounterLong numCreateFile;
Expand Down Expand Up @@ -541,6 +543,17 @@ public void decNumSnapshotDeleted() {
numSnapshotDeleted.incr(-1);
}

public int getNumSnapshotCacheSize() {
return numSnapshotCacheSize.value();
}
public void incNumSnapshotCacheSize() {
numSnapshotCacheSize.incr();
}

public void decNumSnapshotCacheSize() {
numSnapshotCacheSize.decr();
}

public void incNumCompleteMultipartUploadFails() {
numCompleteMultipartUploadFails.incr();
}
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2 changes: 1 addition & 1 deletion hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/OmSnapshotManager.java
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Expand Up @@ -272,7 +272,7 @@ public OmSnapshotManager(OzoneManager ozoneManager) {
};

// Init snapshot cache
this.snapshotCache = new SnapshotCache(loader, softCacheSize);
this.snapshotCache = new SnapshotCache(loader, softCacheSize, ozoneManager.getMetrics());

this.snapshotDiffManager = new SnapshotDiffManager(snapshotDiffDb, differ,
ozoneManager, snapDiffJobCf, snapDiffReportCf,
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11 changes: 9 additions & 2 deletions ...-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/snapshot/SnapshotCache.java
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Expand Up @@ -19,6 +19,7 @@

import com.google.common.annotations.VisibleForTesting;
import com.google.common.cache.CacheLoader;
import org.apache.hadoop.ozone.om.OMMetrics;
import org.apache.hadoop.ozone.om.OmSnapshot;
import org.apache.hadoop.ozone.om.exceptions.OMException;
import org.slf4j.Logger;
Expand Down Expand Up @@ -51,10 +52,13 @@ public class SnapshotCache {
// opened on the OM.
private final int cacheSizeLimit;

public SnapshotCache(CacheLoader<UUID, OmSnapshot> cacheLoader, int cacheSizeLimit) {
private final OMMetrics omMetrics;

public SnapshotCache(CacheLoader<UUID, OmSnapshot> cacheLoader, int cacheSizeLimit, OMMetrics omMetrics) {
this.dbMap = new ConcurrentHashMap<>();
this.cacheLoader = cacheLoader;
this.cacheSizeLimit = cacheSizeLimit;
this.omMetrics = omMetrics;
}

@VisibleForTesting
Expand Down Expand Up @@ -83,6 +87,7 @@ public void invalidate(UUID key) throws IOException {
} catch (IOException e) {
throw new IllegalStateException("Failed to close snapshotId: " + key, e);
}
omMetrics.decNumSnapshotCacheSize();
}
return null;
});
Expand All @@ -104,6 +109,7 @@ public void invalidateAll() {
throw new IllegalStateException("Failed to close snapshot", e);
}
it.remove();
omMetrics.decNumSnapshotCacheSize();
}
}

Expand Down Expand Up @@ -150,14 +156,14 @@ public ReferenceCounted<OmSnapshot> get(UUID key) throws IOException {
// Unexpected and unknown exception thrown from CacheLoader#load
throw new IllegalStateException(ex);
}
omMetrics.incNumSnapshotCacheSize();
}
if (v != null) {
// When RC OmSnapshot is successfully loaded
v.incrementRefCount();
}
return v;
});

if (rcOmSnapshot == null) {
// The only exception that would fall through the loader logic above
// is OMException with FILE_NOT_FOUND.
Expand Down Expand Up @@ -227,6 +233,7 @@ private void cleanupInternal() {
} catch (IOException ex) {
throw new IllegalStateException("Error while closing snapshot DB.", ex);
}
omMetrics.decNumSnapshotCacheSize();
return null;
}
});
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42 changes: 41 additions & 1 deletion ...ne/ozone-manager/src/test/java/org/apache/hadoop/ozone/om/snapshot/TestSnapshotCache.java
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Expand Up @@ -18,6 +18,7 @@
package org.apache.hadoop.ozone.om.snapshot;

import com.google.common.cache.CacheLoader;
import org.apache.hadoop.ozone.om.OMMetrics;
import org.apache.hadoop.ozone.om.OmSnapshot;
import org.apache.ozone.test.GenericTestUtils;
import org.junit.jupiter.api.AfterEach;
Expand Down Expand Up @@ -52,6 +53,8 @@ class TestSnapshotCache {
private static CacheLoader<UUID, OmSnapshot> cacheLoader;
private SnapshotCache snapshotCache;

private OMMetrics omMetrics;

@BeforeAll
static void beforeAll() throws Exception {
cacheLoader = mock(CacheLoader.class);
Expand All @@ -74,7 +77,8 @@ static void beforeAll() throws Exception {
@BeforeEach
void setUp() {
// Reset cache for each test case
snapshotCache = new SnapshotCache(cacheLoader, CACHE_SIZE_LIMIT);
omMetrics = OMMetrics.create();
snapshotCache = new SnapshotCache(cacheLoader, CACHE_SIZE_LIMIT, omMetrics);
}

@AfterEach
Expand All @@ -87,11 +91,13 @@ void tearDown() {
@DisplayName("get()")
void testGet() throws IOException {
final UUID dbKey1 = UUID.randomUUID();
assertEquals(0, omMetrics.getNumSnapshotCacheSize());
ReferenceCounted<OmSnapshot> omSnapshot = snapshotCache.get(dbKey1);
assertNotNull(omSnapshot);
assertNotNull(omSnapshot.get());
assertTrue(omSnapshot.get() instanceof OmSnapshot);
assertEquals(1, snapshotCache.size());
assertEquals(1, omMetrics.getNumSnapshotCacheSize());
}

@Test
Expand All @@ -101,12 +107,14 @@ void testGetTwice() throws IOException {
ReferenceCounted<OmSnapshot> omSnapshot1 = snapshotCache.get(dbKey1);
assertNotNull(omSnapshot1);
assertEquals(1, snapshotCache.size());
assertEquals(1, omMetrics.getNumSnapshotCacheSize());

ReferenceCounted<OmSnapshot> omSnapshot1again = snapshotCache.get(dbKey1);
// Should be the same instance
assertEquals(omSnapshot1, omSnapshot1again);
assertEquals(omSnapshot1.get(), omSnapshot1again.get());
assertEquals(1, snapshotCache.size());
assertEquals(1, omMetrics.getNumSnapshotCacheSize());
}

@Test
Expand All @@ -117,10 +125,12 @@ void testReleaseByDbKey() throws IOException {
assertNotNull(omSnapshot1);
assertNotNull(omSnapshot1.get());
assertEquals(1, snapshotCache.size());
assertEquals(1, omMetrics.getNumSnapshotCacheSize());

snapshotCache.release(dbKey1);
// Entry will not be immediately evicted
assertEquals(1, snapshotCache.size());
assertEquals(1, omMetrics.getNumSnapshotCacheSize());
}

@Test
Expand All @@ -130,13 +140,16 @@ void testInvalidate() throws IOException {
ReferenceCounted<OmSnapshot> omSnapshot = snapshotCache.get(dbKey1);
assertNotNull(omSnapshot);
assertEquals(1, snapshotCache.size());
assertEquals(1, omMetrics.getNumSnapshotCacheSize());

snapshotCache.release(dbKey1);
// Entry will not be immediately evicted
assertEquals(1, snapshotCache.size());
assertEquals(1, omMetrics.getNumSnapshotCacheSize());

snapshotCache.invalidate(dbKey1);
assertEquals(0, snapshotCache.size());
assertEquals(0, omMetrics.getNumSnapshotCacheSize());
}

@Test
Expand All @@ -146,28 +159,34 @@ void testInvalidateAll() throws IOException {
ReferenceCounted<OmSnapshot> omSnapshot1 = snapshotCache.get(dbKey1);
assertNotNull(omSnapshot1);
assertEquals(1, snapshotCache.size());
assertEquals(1, omMetrics.getNumSnapshotCacheSize());

final UUID dbKey2 = UUID.randomUUID();
ReferenceCounted<OmSnapshot> omSnapshot2 = snapshotCache.get(dbKey2);
assertNotNull(omSnapshot2);
assertEquals(2, snapshotCache.size());
assertEquals(2, omMetrics.getNumSnapshotCacheSize());
// Should be difference omSnapshot instances
assertNotEquals(omSnapshot1, omSnapshot2);

final UUID dbKey3 = UUID.randomUUID();
ReferenceCounted<OmSnapshot> omSnapshot3 = snapshotCache.get(dbKey3);
assertNotNull(omSnapshot3);
assertEquals(3, snapshotCache.size());
assertEquals(3, omMetrics.getNumSnapshotCacheSize());

snapshotCache.release(dbKey1);
// Entry will not be immediately evicted
assertEquals(3, snapshotCache.size());
assertEquals(3, omMetrics.getNumSnapshotCacheSize());

snapshotCache.invalidate(dbKey1);
assertEquals(2, snapshotCache.size());
assertEquals(2, omMetrics.getNumSnapshotCacheSize());

snapshotCache.invalidateAll();
assertEquals(0, snapshotCache.size());
assertEquals(0, omMetrics.getNumSnapshotCacheSize());
}

private void assertEntryExistence(UUID key, boolean shouldExist) {
Expand All @@ -191,26 +210,33 @@ void testEviction1() throws IOException {
final UUID dbKey1 = UUID.randomUUID();
snapshotCache.get(dbKey1);
assertEquals(1, snapshotCache.size());
assertEquals(1, omMetrics.getNumSnapshotCacheSize());
snapshotCache.release(dbKey1);
assertEquals(1, snapshotCache.size());
assertEquals(1, omMetrics.getNumSnapshotCacheSize());

final UUID dbKey2 = UUID.randomUUID();
snapshotCache.get(dbKey2);
assertEquals(2, snapshotCache.size());
assertEquals(2, omMetrics.getNumSnapshotCacheSize());
snapshotCache.release(dbKey2);
assertEquals(2, snapshotCache.size());
assertEquals(2, omMetrics.getNumSnapshotCacheSize());

final UUID dbKey3 = UUID.randomUUID();
snapshotCache.get(dbKey3);
assertEquals(3, snapshotCache.size());
assertEquals(3, omMetrics.getNumSnapshotCacheSize());
snapshotCache.release(dbKey3);
assertEquals(3, snapshotCache.size());
assertEquals(3, omMetrics.getNumSnapshotCacheSize());

final UUID dbKey4 = UUID.randomUUID();
snapshotCache.get(dbKey4);
// dbKey1, dbKey2 and dbKey3 would have been evicted by the end of the last get() because
// those were release()d.
assertEquals(1, snapshotCache.size());
assertEquals(1, omMetrics.getNumSnapshotCacheSize());
assertEntryExistence(dbKey1, false);
}

Expand All @@ -221,25 +247,30 @@ void testEviction2() throws IOException {
final UUID dbKey1 = UUID.randomUUID();
snapshotCache.get(dbKey1);
assertEquals(1, snapshotCache.size());
assertEquals(1, omMetrics.getNumSnapshotCacheSize());

final UUID dbKey2 = UUID.randomUUID();
snapshotCache.get(dbKey2);
assertEquals(2, snapshotCache.size());
assertEquals(2, omMetrics.getNumSnapshotCacheSize());

final UUID dbKey3 = UUID.randomUUID();
snapshotCache.get(dbKey3);
assertEquals(3, snapshotCache.size());
assertEquals(3, omMetrics.getNumSnapshotCacheSize());

final UUID dbKey4 = UUID.randomUUID();
snapshotCache.get(dbKey4);
// dbKey1 would not have been evicted because it is not release()d
assertEquals(4, snapshotCache.size());
assertEquals(4, omMetrics.getNumSnapshotCacheSize());
assertEntryExistence(dbKey1, true);

// Releasing dbKey2 at this point should immediately trigger its eviction
// because the cache size exceeded the soft limit
snapshotCache.release(dbKey2);
assertEquals(3, snapshotCache.size());
assertEquals(3, omMetrics.getNumSnapshotCacheSize());
assertEntryExistence(dbKey2, false);
assertEntryExistence(dbKey1, true);
}
Expand All @@ -252,41 +283,50 @@ void testEviction3WithClose() throws IOException {
try (ReferenceCounted<OmSnapshot> rcOmSnapshot = snapshotCache.get(dbKey1)) {
assertEquals(1L, rcOmSnapshot.getTotalRefCount());
assertEquals(1, snapshotCache.size());
assertEquals(1, omMetrics.getNumSnapshotCacheSize());
}
// ref count should have been decreased because it would be close()d
// upon exiting try-with-resources.
assertEquals(0L, snapshotCache.getDbMap().get(dbKey1).getTotalRefCount());
assertEquals(1, snapshotCache.size());
assertEquals(1, omMetrics.getNumSnapshotCacheSize());

final UUID dbKey2 = UUID.randomUUID();
try (ReferenceCounted<OmSnapshot> rcOmSnapshot = snapshotCache.get(dbKey2)) {
assertEquals(1L, rcOmSnapshot.getTotalRefCount());
assertEquals(2, snapshotCache.size());
assertEquals(2, omMetrics.getNumSnapshotCacheSize());
// Get dbKey2 entry a second time
try (ReferenceCounted<OmSnapshot> rcOmSnapshot2 = snapshotCache.get(dbKey2)) {
assertEquals(2L, rcOmSnapshot.getTotalRefCount());
assertEquals(2L, rcOmSnapshot2.getTotalRefCount());
assertEquals(2, snapshotCache.size());
assertEquals(2, omMetrics.getNumSnapshotCacheSize());
}
assertEquals(1L, rcOmSnapshot.getTotalRefCount());
}
assertEquals(0L, snapshotCache.getDbMap().get(dbKey2).getTotalRefCount());
assertEquals(2, snapshotCache.size());
assertEquals(2, omMetrics.getNumSnapshotCacheSize());

final UUID dbKey3 = UUID.randomUUID();
try (ReferenceCounted<OmSnapshot> rcOmSnapshot = snapshotCache.get(dbKey3)) {
assertEquals(1L, rcOmSnapshot.getTotalRefCount());
assertEquals(3, snapshotCache.size());
assertEquals(3, omMetrics.getNumSnapshotCacheSize());
}
assertEquals(0L, snapshotCache.getDbMap().get(dbKey3).getTotalRefCount());
assertEquals(3, snapshotCache.size());
assertEquals(3, omMetrics.getNumSnapshotCacheSize());

final UUID dbKey4 = UUID.randomUUID();
try (ReferenceCounted<OmSnapshot> rcOmSnapshot = snapshotCache.get(dbKey4)) {
assertEquals(1L, rcOmSnapshot.getTotalRefCount());
assertEquals(1, snapshotCache.size());
assertEquals(1, omMetrics.getNumSnapshotCacheSize());
}
assertEquals(0L, snapshotCache.getDbMap().get(dbKey4).getTotalRefCount());
assertEquals(1, snapshotCache.size());
assertEquals(1, omMetrics.getNumSnapshotCacheSize());
}
}
2 changes: 1 addition & 1 deletion ...ne-manager/src/test/java/org/apache/hadoop/ozone/om/snapshot/TestSnapshotDiffManager.java
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Expand Up @@ -377,7 +377,7 @@ public void init() throws RocksDBException, IOException, ExecutionException {

omSnapshotManager = mock(OmSnapshotManager.class);
when(omSnapshotManager.isSnapshotStatus(any(), any())).thenReturn(true);
SnapshotCache snapshotCache = new SnapshotCache(mockCacheLoader(), 10);
SnapshotCache snapshotCache = new SnapshotCache(mockCacheLoader(), 10, omMetrics);

when(omSnapshotManager.getActiveSnapshot(anyString(), anyString(), anyString()))
.thenAnswer(invocationOnMock -> {
Expand Down

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