"make tests" failed with NullPointerException

[JerryYangSH]

/usr/lib/jvm/jdk1.8.0_231/bin/javac  -Xlint:unchecked -XDenableSunApiLintControl -proc:none -d target/test_classes -cp src:target/classes:lib:src:lib/ST-4.0.8.jar: src/test/java/tests/PersistentLinkedQueueTest.java src/test/java/tests/PersistentLinkedListTest.java src/test/java/tests/TestCases.java src/test/java/tests/PersistentSIHashMapTest.java src/test/java/tests/PersistentFPTree2Test.java src/test/java/tests/PersistentArrayTest.java src/test/java/tests/PersistentTestRunner.java src/test/java/tests/ObjectDirectoryTest.java src/test/java/tests/PersistentFPTree1Test.java src/test/java/tests/PersistentHashMapTest.java src/test/java/tests/PersistentTupleTest.java src/test/java/tests/PersistentAtomicReferenceTest.java src/test/java/tests/PersistentSkipListMapTest.java src/test/java/tests/MultithreadTest.java src/test/java/tests/PersistentByteBufferTest.java src/test/java/tests/PersistentArrayListTest.java
Picked up JAVA_TOOL_OPTIONS: -Dfile.encoding=UTF-8 -Djava.library.path=/usr/local/lib
/usr/lib/jvm/jdk1.8.0_231/bin/java  -ea -cp target/classes:lib:src:lib/ST-4.0.8.jar::target/test_classes:src -Djava.library.path=target/cppbuild tests.PersistentTestRunner
Picked up JAVA_TOOL_OPTIONS: -Dfile.encoding=UTF-8 -Djava.library.path=/usr/local/lib
Opening heap... Exception in thread "main" java.lang.ExceptionInInitializerError
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:264)
        at lib.util.persistent.ClassInfo.initReconstructor(ClassInfo.java:139)
        at lib.util.persistent.ClassInfo.<init>(ClassInfo.java:74)
        at lib.util.persistent.ClassInfo.init(ClassInfo.java:125)
        at lib.xpersistent.XHeap.open(XHeap.java:83)
        at tests.PersistentTestRunner.main(PersistentTestRunner.java:32)
Caused by: java.lang.NullPointerException
        at lib.util.persistent.ObjectCache.lambda$objectForAddress$2(ObjectCache.java:184)
        at lib.util.persistent.Util.synchronizedBlock(Util.java:119)
        at lib.util.persistent.ObjectCache.objectForAddress(ObjectCache.java:172)
        at lib.util.persistent.ObjectCache.getReference(ObjectCache.java:137)
        at lib.util.persistent.ObjectCache.get(ObjectCache.java:120)
        at lib.util.persistent.ObjectCache.get(ObjectCache.java:114)
        at lib.util.persistent.AbstractPersistentMutableArray.getObject(AbstractPersistentMutableArray.java:85)
        at lib.util.persistent.AnyPersistent.getObject(AnyPersistent.java:221)
        at lib.util.persistent.AbstractPersistentArray.getObjectElement(AbstractPersistentArray.java:70)
        at lib.util.persistent.PersistentArray.get(PersistentArray.java:86)
        at lib.util.persistent.PersistentHashMap.getNode(PersistentHashMap.java:427)
        at lib.util.persistent.PersistentHashMap.get(PersistentHashMap.java:303)
        at lib.util.persistent.ObjectDirectory.get(ObjectDirectory.java:36)
        at lib.util.persistent.PersistentArrayList.<clinit>(PersistentArrayList.java:57)
        ... 7 more
make: *** [Makefile:83: tests] Error 1

relevent code is in ObjectCache.java:

@SuppressWarnings("unchecked")
    static <T extends AnyPersistent> Ref<T> objectForAddress(long address, boolean forAdmin) {
        final Address addr =  new Address(address);
        return Util.synchronizedBlock(cacheLock, ()->{ 
        Ref<T> ans = null;
        if ((ans = (Ref<T>)cache.get(addr)) != null && ans.get() != null) {
                 // trace(true, address, "OFA HIT: in OC");
            // assert(ans.get() != null);
            return ans; 
        }
        else {
            T obj = null;
            MemoryRegion region = new UncheckedPersistentMemoryRegion(address);
            long classInfoAddress = region.getLong(0);
            ClassInfo ci = ClassInfo.getClassInfo(classInfoAddress);  // ci is Null !!!
            ObjectType<T> type = Types.typeForName(ci.className());
            obj = AnyPersistent.reconstruct(new ObjectPointer<T>((ObjectType)type, region));
            ans = new Ref(obj, forAdmin);
            if (!Transaction.addReconstructedObject(address, ans)) cache.put(addr, ans);
        }
        return ans; 
        });
    }```

On ubuntu 19.
jerry@u19:~/opensources/pcj$ sudo fdisk -l /dev/pmem0
Disk /dev/pmem0: 4 GiB, 4294967296 bytes, 8388608 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes

jerry@u19:~/opensources/pcj$ mount | grep pmem0
/dev/pmem0 on /mnt/mem type ext4 (rw,relatime,dax)

[asonje]

Hi Jerry could you describe the steps to reproduce this. Do you run 'make tests' with a clean heap? Thanks

[JerryYangSH]

@asonje I did clean everything (make clean and rm -rf /mnt/mem/* ) to run 'make tests'. This issue would likely happen when key op count or test time increases. I wrote a BasicBenchMarkTest to demo this. https://github.com/JerryYangSH/pcj/blob/master/src/test/java/tests/BasicBenchmarkTest.java

1.copy BasicBenchmarkTest.java into your codebase,
2. rm -rf /mnt/mem/* && make clean&& make && make tests

Opening heap... Cleaning up heap... Heap opened.
****************BasicBenchmarkTest Tests**********************
*Time Bound Testing PersistentFPTree2 (Single Thread, 100000 keys)
[Timer Bound Test     10s] avg lat:
          DELETE :       37 (us)
          CREATE :       66 (us)
             GET :       30 (us)
          UPDATE :       36 (us)
[Timer Bound Test     60s] avg lat:
Exception in thread "Thread-0" java.lang.NullPointerException
        at lib.util.persistent.AnyPersistent.getChildAddressIterator(AnyPersistent.java:518)
        at lib.util.persistent.AnyPersistent.lambda$deleteReference$10(AnyPersistent.java:474)
        at lib.util.persistent.Transaction.lambda$run$2(Transaction.java:169)
        at lib.util.persistent.Transaction.run(Transaction.java:120)
        at lib.util.persistent.Transaction.run(Transaction.java:88)
        at lib.util.persistent.Transaction.run(Transaction.java:169)
        at lib.util.persistent.AnyPersistent.deleteReference(AnyPersistent.java:463)
        at lib.util.persistent.ObjectCache.lambda$static$1(ObjectCache.java:79)
        at java.lang.Thread.run(Thread.java:748)
          DELETE :       48 (us)
          CREATE :       74 (us)
             GET :      229 (us)
          UPDATE :       65 (us)
[Timer Bound Test    300s] avg lat:
Exception in thread "Thread-10" java.lang.NullPointerException
        at lib.util.persistent.ObjectCache.uncommittedConstruction(ObjectCache.java:218)
        at lib.util.persistent.Transaction.addReconstructedObject(Transaction.java:251)
        at lib.util.persistent.ObjectCache.lambda$objectForAddress$2(ObjectCache.java:187)
        at lib.util.persistent.Util.synchronizedBlock(Util.java:125)
        at lib.util.persistent.ObjectCache.objectForAddress(ObjectCache.java:172)
        at lib.util.persistent.ObjectCache.getReference(ObjectCache.java:137)
        at lib.util.persistent.ObjectCache.get(ObjectCache.java:120)
        at lib.util.persistent.ObjectCache.get(ObjectCache.java:114)
        at lib.util.persistent.AbstractPersistentMutableArray.getObject(AbstractPersistentMutableArray.java:85)
        at lib.util.persistent.AnyPersistent.getObject(AnyPersistent.java:221)
        at lib.util.persistent.AbstractPersistentArray.getObjectElement(AbstractPersistentArray.java:70)
        at lib.util.persistent.PersistentArray.get(PersistentArray.java:86)
        at lib.util.persistent.PersistentFPTree2$PersistentLeaf.getSlot(PersistentFPTree2.java:1722)
        at lib.util.persistent.PersistentFPTree2.lambda$splitLeafNodeAndUpdateParent$14(PersistentFPTree2.java:1220)
        at lib.util.persistent.Transaction.lambda$run$7(Transaction.java:189)
        at lib.util.persistent.Transaction.run(Transaction.java:120)
        at lib.util.persistent.Transaction.run(Transaction.java:88)
        at lib.util.persistent.Transaction.run(Transaction.java:189)
        at lib.util.persistent.PersistentFPTree2.splitLeafNodeAndUpdateParent(PersistentFPTree2.java:1217)
        at lib.util.persistent.PersistentFPTree2.splitLeafNodeAndUpdateParent(PersistentFPTree2.java:1210)
        at lib.util.persistent.PersistentFPTree2.splitChildAndUpdateParent(PersistentFPTree2.java:1203)
        at lib.util.persistent.PersistentFPTree2.doPut(PersistentFPTree2.java:1023)
        at lib.util.persistent.PersistentFPTree2.put(PersistentFPTree2.java:991)
        at lib.util.persistent.PersistentFPTree2.put(PersistentFPTree2.java:77)
        at tests.BasicBenchmarkTest.lambda$testBenchmarkTimeBound$0(BasicBenchmarkTest.java:213)
        at tests.BasicBenchmarkTest$TimerTestTask.run(BasicBenchmarkTest.java:257)
        at java.lang.Thread.run(Thread.java:748)

And it eventually hungs here.

My setup is as below:

jerry@u19:~/opensources/pcj$ cat config.properties
path=/mnt/mem/persistent_heap
size=2147483648jerry@u19:~/opensources/pcj$ !sudo
sudo fdisk -l /dev/pmem0
Disk /dev/pmem0: 4 GiB, 4225761280 bytes, 8253440 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes

jerry@u19:~/opensources/pcj$ sudo fdisk -l /dev/pmem0
Disk /dev/pmem0: 4 GiB, 4225761280 bytes, 8253440 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
jerry@u19:~/opensources/pcj$ ls -lh /mnt/mem/
total 2.1G
-rw------- 1 jerry jerry 2.0G Dec 20 02:56 persistent_heap
jerry@u19:~/opensources/pcj$ mount | grep pmem0
/dev/pmem0 on /mnt/mem type ext4 (rw,relatime,dax)