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8225084: gc/z/TestHighUsage.java fails with unexpected allocation stall

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Reviewed-by: eosterlund
This commit is contained in:
Per Lidén 2019-06-05 10:43:45 +02:00
parent 8db95fbee9
commit 0b647d15bf
1 changed files with 17 additions and 17 deletions
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34
test/hotspot/jtreg/gc/z/TestHighUsage.java
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@ -38,18 +38,21 @@ public class TestHighUsage {
static class Test {
private static final int K = 1024;
private static final int M = K * K;
private static final long startAt = 16 * M;
private static final long spikeAt = 4 * M;
private static final long maxCapacity = Runtime.getRuntime().maxMemory();
private static final long slowAllocationThreshold = 16 * M;
private static final long highUsageThreshold = maxCapacity / 20; // 5%
private static volatile LinkedList<byte[]> keepAlive;
private static volatile Object dummy;
public static void main(String[] args) throws Exception {
System.out.println("Max capacity: " + (maxCapacity / M) + "M");
System.out.println("High usage threshold: " + (highUsageThreshold / M) + "M");
System.out.println("Allocating live-set");
// Allocate live-set
keepAlive = new LinkedList<>();
while (Runtime.getRuntime().freeMemory() > startAt) {
while (Runtime.getRuntime().freeMemory() > startAt) {
while (Runtime.getRuntime().freeMemory() > slowAllocationThreshold) {
while (Runtime.getRuntime().freeMemory() > slowAllocationThreshold) {
keepAlive.add(new byte[128 * K]);
}
@ -60,21 +63,18 @@ public class TestHighUsage {
System.out.println("Allocating garbage slowly");
// Allocate garbage slowly, such that the sampled allocation rate on
// average becomes zero MB/s for the last 1 second windows. If free
// memory goes below the spike limit we induce an allocation spike.
// The expected behavior is that the "High Usage" rule kicks in before
// the spike happens, avoiding an "Allocation Stall".
// Allocate garbage slowly, so that the sampled allocation rate on average
// becomes zero MB/s for the last 1 second windows. Once we reach the high
// usage threshold we idle to allow for a "High Usage" GC cycle to happen.
// We need to allocate slowly to avoid an "Allocation Rate" GC cycle.
for (int i = 0; i < 300; i++) {
final long free = Runtime.getRuntime().freeMemory();
System.out.println("Free: " + (free / M) + "M");
if (free > spikeAt) {
// Low allocation rate
if (Runtime.getRuntime().freeMemory() > highUsageThreshold) {
// Allocate
dummy = new byte[128 * K];
System.out.println("Free: " + (Runtime.getRuntime().freeMemory() / M) + "M (Allocating)");
} else {
// High allocation rate
dummy = new byte[8 * M];
// Idle
System.out.println("Free: " + (Runtime.getRuntime().freeMemory() / M) + "M (Idling)");
}
Thread.sleep(250);
@ -93,7 +93,7 @@ public class TestHighUsage {
"-Xmx128M",
"-XX:ParallelGCThreads=1",
"-XX:ConcGCThreads=1",
"-Xlog:gc",
"-Xlog:gc,gc+start",
Test.class.getName() })
.shouldNotContain("Allocation Stall")
.shouldContain("High Usage")