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This commit is contained in:
tstuefe 2026-01-26 11:08:21 +01:00
parent e820ad5432
commit efcf905a43
2 changed files with 36 additions and 47 deletions
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2
test/jdk/jdk/jfr/jcmd/TestJcmdDumpPathToGCRootsBFSDFS.java
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@ -47,7 +47,7 @@ import jdk.test.lib.jfr.EventNames;
* @modules jdk.jfr/jdk.jfr.internal.test
* @library /test/lib /test/jdk
*
* @run main/othervm -XX:TLABSize=2k -Xmx256m -Xlog:jfr+system+dfs jdk.jfr.jcmd.TestJcmdDumpPathToGCRootsBFSDFS dfs-only
* @run main/othervm -XX:TLABSize=2k -Xmx256m jdk.jfr.jcmd.TestJcmdDumpPathToGCRootsBFSDFS dfs-only
*/
/**

81
test/jdk/jdk/jfr/jcmd/TestJcmdDumpPathToGCRootsDFSWithSmallStack.java
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@ -23,6 +23,10 @@
package jdk.jfr.jcmd;
import java.io.File;
import java.io.IOException;
import java.util.*;
import jdk.jfr.Enabled;
import jdk.jfr.Recording;
import jdk.jfr.consumer.RecordedEvent;
@ -31,65 +35,47 @@ import jdk.jfr.consumer.RecordingFile;
import jdk.jfr.internal.test.WhiteBox;
import jdk.test.lib.jfr.EventNames;
import java.io.File;
import java.io.IOException;
import java.util.*;
// This test tests that even with a rather small stack size we can execute path-to-gc-roots search in
// leak profiler.
// (Note: VMThreadStackSize dictates stack size for *all* VM threads, not just the VMThread; therefore
// we cannot go infinitly low)
/**
* @test id=dfs-only
* @summary Test dumping with path-to-gc-roots and DFS only, with a very small VMThread stack size
* @summary Test dumping with path-to-gc-roots and DFS only with a very small stacksize for the VM thread
* @requires vm.hasJFR & vm.flagless
* @modules jdk.jfr/jdk.jfr.internal.test
* @library /test/lib /test/jdk
*
* @run main/othervm -Xmx1g -XX:VMThreadStackSize=128k -Xlog:jfr+system+dfs jdk.jfr.jcmd.TestJcmdDumpPathToGCRootsBFSDFS dfs-only
*/
/**
* @test id=bfsdfs
* @summary Test dumping with path-to-gc-roots and mixed BFS+DFS, with a very small VMThread stack size
* @bug 8373490
* @requires vm.hasJFR & vm.flagless
* @modules jdk.jfr/jdk.jfr.internal.test
* @library /test/lib /test/jdk
*
* @run main/othervm -Xmx1g -XX:VMThreadStackSize=128k -Xlog:jfr+system+dfs jdk.jfr.jcmd.TestJcmdDumpPathToGCRootsBFSDFS bfsdfs
* @run main/othervm -Xmx1g -XX:VMThreadStackSize=128 jdk.jfr.jcmd.TestJcmdDumpPathToGCRootsDFSWithSmallStack dfs-only
*/
public class TestJcmdDumpPathToGCRootsDFSWithSmallStack {
// Note for BFS-DFS: in order to force the JVM to take the BFS-DFS path instead of just doing things BFS-only,
// we start with a small heap of 256M. That gives us a (low-capped) BFS edge queue size of 32M. We then build up
// a leak with > 2mio entries, which will exhaust the edge queue eventually and cause BFS to invoke the DFS fallback.
// Tests the new non-recursive implementation of the JFR leak profiler path-to-gc-roots-search.
// The minimum size of the edge queue in BFS (keep in sync with hotspot)
// see edge_queue_memory_reservation() in pathToGCRootsOperation.cpp
private final static int minimumEdgeQueueSizeCap = 32 * 1024 * 1024;
// We build up an array of linked lists, each containing enough entries for DFS search to
// max out max_dfs_depth (but not greatly surpass it).
// The old recursive implementation, started with such a small stack, will fail to reach
// max_dfs_depth, instead crashing with stack overflow.
// The new non-recursive implementation should work; the majority of the linked list items
// should be scanned (all those at the start of the lists, below max_dfs_depth) and contribute
// old object samples to the result.
private static List<Object[]> leak;
private final static int leakedObjectCount = 5_000_000;
// Note: VMThreadStackSize defines thread stack size for *all* VM-internal threads, not just the
// VM thread. Make sure that whatever small size we use in this test is still fine for the rest of
// the VM.
private static final int TOTAL_OBJECTS = 10_000_000;
private static final int OBJECTS_PER_LIST = 5_000;
private static LinkedList[] leak;
public static void main(String[] args) throws Exception {
WhiteBox.setWriteAllObjectSamples(true);
String settingName = EventNames.OldObjectSample + "#" + "cutoff";
boolean skipBFS = switch (args[0]) {
case "bfsdfs" -> false;
case "dfs-only" -> true;
default -> {
throw new RuntimeException("Invalid argument");
}
};
int leakedObjectCount = 10_000_000;
boolean skipBFS = true;
WhiteBox.setSkipBFS(skipBFS);
testDump(Collections.singletonMap(settingName, "infinity"));
testDump(Collections.singletonMap(settingName, "infinity"), leakedObjectCount);
}
private static void testDump(Map<String, String> settings) throws Exception {
private static void testDump(Map<String, String> settings, int leakedObjectCount) throws Exception {
final String pathToGcRoots = "path-to-gc-roots=true";
int numTries = 3;
while (--numTries >= 0) {
@ -107,7 +93,7 @@ public class TestJcmdDumpPathToGCRootsDFSWithSmallStack {
buildLeak(leakedObjectCount);
System.gc();
System.gc();
File recording = new File("TestJcmdDumpPathToGCRoots" + r.getId() + ".jfr");
File recording = new File("TestJcmdDumpPathToGCRootsDFSWithSmallStack" + r.getId() + ".jfr");
recording.delete();
JcmdHelper.jcmd("JFR.dump", "name=dodo", pathToGcRoots, "filename=" + recording.getAbsolutePath());
r.setSettings(Collections.emptyMap());
@ -117,7 +103,7 @@ public class TestJcmdDumpPathToGCRootsDFSWithSmallStack {
continue;
}
int chains = countChains(events);
final int minNumberOfChains = 20; // very conservative; normally 130-160
final int minNumberOfChains = 30; // very conservative; normally ~250
if (chains < minNumberOfChains) {
System.out.println(events);
System.out.println("Not enough chains found (" + chains + "), retrying.");
@ -130,8 +116,8 @@ public class TestJcmdDumpPathToGCRootsDFSWithSmallStack {
}
private static void clearLeak() {
leak = null;
System.gc();
leak = null;
System.gc();
}
private static int countChains(List<RecordedEvent> events) throws IOException {
@ -147,9 +133,12 @@ public class TestJcmdDumpPathToGCRootsDFSWithSmallStack {
}
private static void buildLeak(int objectCount) {
leak = new ArrayList<Object[]>(objectCount);
for (int i = 0; i < objectCount;i ++) {
leak.add(new Object[0]);
leak = new LinkedList[TOTAL_OBJECTS/OBJECTS_PER_LIST];
for (int i = 0; i < leak.length; i++) {
leak[i] = new LinkedList();
for (int j = 0; j < OBJECTS_PER_LIST; j++) {
leak[i].add(new Object());
}
}
}
}