The code below dumps a heap with ~86mb cacheChunkRef. If you bump
OUTER_LOOP_COUNT to 1,000,000, it dumps a heap with ~469mb cacheChunkRef.
public class MVStoreTest {
private static final int OUTER_LOOP_COUNT = 100000;
public static void main(String[] args) throws Exception {
Connection connection =
DriverManager.getConnection("jdbc:h2:~/test;compress=true",
"sa", "");
Statement statement = connection.createStatement();
statement.execute("create table xyz (x varchar, y bigint)");
statement.execute("create index xyz_idx on xyz (x, y)");
PreparedStatement preparedStatement =
connection.prepareStatement("insert into xyz (x, y) values
(?, ?)");
long start = System.currentTimeMillis();
for (int i = 0; i < OUTER_LOOP_COUNT; i++) {
for (int j = 0; j < 100; j++) {
preparedStatement.setString(1, "x" + j);
preparedStatement.setLong(2, i);
preparedStatement.addBatch();
}
preparedStatement.executeBatch();
if ((i + 1) % 1000 == 0) {
long end = System.currentTimeMillis();
System.out.println((i + 1) + " " + (end - start));
start = end;
}
}
ManagementFactory.getPlatformMBeanServer().invoke(
ObjectName.getInstance("com.sun.management:type=HotSpotDiagnostic"),
"dumpHeap",
new Object[] {"heapdump.hprof", true},
new String[] {"java.lang.String", "boolean"});
connection.close();
}
}
On Wednesday, February 11, 2015 at 10:56:18 PM UTC-8, Thomas Mueller wrote:
>
> Hi,
>
> That means the LIRS cache keeps too many non-resident cold entries. I
> wonder how to best reproduce this problem... Do you have a simple test case
> (a description what you do would be enough in this case)?
>
> Regards,
> Thomas
>
> On Thu, Feb 12, 2015 at 3:17 AM, Trask Stalnaker <trask.s...@gmail.com
> <javascript:>> wrote:
>
>> Hi,
>>
>> I was looking over a heap dump and was surprised by MVStore.cacheChunkRef
>> consuming 29mb memory.
>>
>> MVStore.cache is consuming 14mb which makes sense given the 16mb default
>> cache limit.
>>
>> Eclipse MemoryAnalyzer OQL shows 100,000+
>> org.h2.mvstore.cache.CacheLongKeyLIRS$Entry objects with memory = 0 and
>> value = null:
>>
>> select * from org.glowroot.shaded.h2.mvstore.cache.CacheLongKeyLIRS$Entry
>> where value = null and memory = 0
>>
>>
>> Is this memory consumption expected? Is there a concern memory may grow
>> unbounded given enough of these objects with memory = 0 since H2 won't
>> count them against it's internal memory limit?
>>
>> Using latest 1.4.185.
>>
>> Thanks,
>> Trask
>>
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