Home

Awesome

Polarbear

A tool to help diagnose OutOfMemoryError conditions.

Polarbear helps track down the root cause of OutOfMemoryError exceptions in Java. When the JVM runs out of memory, polarbear will log detailed information about what threads are running and what objects are live to /tmp/oom.log for later review.

Status:

This is a very early stage project. It works for our needs. We haven't verified it works beyond that. Issue reports and patches are very much appreciated!

Installation

OS X:

gnumake J2SDK=/System/Library/Frameworks/JavaVM.framework/Versions/1.6/Home OSNAME=darwin clean test

Ubuntu:

make J2SDK=/usr/lib/jvm/java-1.6.0-openjdk OSNAME=linux clean test

Running make will build a JVMTI library. You can enable with a command line flag like the following:

-agentpath:/path/to/liboutOfMemory.so=ImportantClass,AnotherImportantClass

This will produce the normal output (see Sample Output below) in addition to calculating retained sizes for ImportantClass and AnotherImportantClass instances.

polarbear shell

polarbear provides a limited repl on 8787 that allows you to interact directly.

Note: 8787 is not secure or fault tolerant and MUST be protected in other ways

> telnet localhost 8787

histogram

[...]

stats Lorg/apache/lucene/index/IndexWriter;

[...]

Sample Output

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
        at java.lang.StringBuilder.toString(StringBuilder.java:430)
        at Test.main(Test.java:16)
Initializing polarbear.

Performing retained size analysis for 2 classes:
HashMap
OOMList

About to throw an OutOfMemory error.
Suspending all threads except the current one.
Printing a heap histogram.
Heap View, Total of 799172 objects found.

Space      Count      Retained   Class Signature
---------- ---------- ---------- ----------------------
  31692904     396154          0 [C
Collecting references... Finding references to references... Aggregating references...
                Level 1 referrers:
                    396191 Ljava/lang/String;
                         3 Ljava/lang/Thread;
                         1 Ljava/lang/ThreadLocal$ThreadLocalMap$Entry;
                         1 Ljava/lang/ref/Finalizer$FinalizerThread;
                         1 Ljava/lang/ref/Reference$ReferenceHandler;
                         2 Ljava/io/BufferedWriter;
                         1 Ljava/lang/StringBuilder;

                Level 2 referrers:
                       313 [Ljava/lang/Object;
                       314 Ljava/util/HashMap$Entry;
                       166 Ljava/util/LinkedHashMap$Entry;
                       309 Ljava/util/Hashtable$Entry;
                       186 Ljava/util/LinkedList$Entry;
                       259 Ljava/lang/Integer;
                         8 Lsun/security/util/ObjectIdentifier;
                        48 Ljava/security/Provider$Service;
                        40 Ljava/net/URL;
                        59 [Ljava/lang/String;
                        93 Ljava/security/Provider$ServiceKey;
                        46 Ljava/security/Provider$UString;
                        31 Ljava/util/concurrent/ConcurrentHashMap$HashEntry;
                        30 Ljava/security/Provider$EngineDescription;
                        16 Ljava/util/jar/JarFile;
                        23 Lsun/security/x509/OIDMap$OIDInfo;
                        28 Ljava/io/ExpiringCache$Entry;
                        16 Ljava/io/ObjectStreamField;
                        19 Ljava/util/Locale;
                        18 Lsun/security/x509/RDN;
                        21 Lsun/security/x509/AVAKeyword;
                         4 Ljava/lang/reflect/Method;
                        17 Ljava/util/jar/Attributes$Name;
                        11 Lsun/security/jca/ProviderConfig;
                         4 Ljava/util/jar/JarFile$JarFileEntry;
                         1 Ljava/lang/ref/WeakReference;
                         4 Ljava/lang/OutOfMemoryError;
                         1 [Ljava/lang/ThreadLocal$ThreadLocalMap$Entry;
                         2 Lsun/security/provider/Sun;
                         3 Lsun/security/x509/X500Name;
                         7 Lsun/security/x509/NetscapeCertTypeExtension$MapEntry;
                         2 Ljava/lang/reflect/Field;
                         2 Lsun/nio/cs/MacRoman$Encoder;
                         2 Lsun/security/x509/X509CertImpl;
                         5 Lsun/security/jca/ServiceId;
                         4 Ljava/io/File;
                         1 Lsun/security/jca/ProviderList$1;
                         2 Ljava/lang/ThreadGroup;
                         2 Ljava/util/Properties;
                         4 Ljava/text/Normalizer$Form;
                         3 Lsun/misc/Signal;
                         3 Ljava/lang/RuntimePermission;
                         2 Ljava/security/AlgorithmParameters;
                         2 Ljava/io/PrintStream;
                         2 [Ljava/lang/Thread;
                         3 Ljava/nio/charset/CodingErrorAction;
                         1 Ljava/io/UnixFileSystem;
                         1 Ljava/lang/ArithmeticException;
                         1 Ljava/lang/ClassLoader$NativeLibrary;
                         1 Ljava/io/FilePermission;
                         1 Lsun/nio/cs/StandardCharsets;
                         2 Ljava/nio/ByteOrder;
                         1 Lcom/apple/java/Usage;
                         1 Ljava/lang/reflect/ReflectPermission;
                         1 Lsun/nio/cs/US_ASCII;
                         1 Lsun/security/provider/certpath/X509CertPath;
                         1 Lsun/nio/cs/UTF_8;
                         1 Lsun/nio/cs/MacRoman;
                         1 Lsun/security/x509/RFC822Name;

                Level 3 referrers:
                        10 [Ljava/lang/Object;
                        62 [Ljava/util/HashMap$Entry;
                        49 Ljava/util/HashMap$Entry;
                        96 Ljava/util/LinkedHashMap$Entry;
                         6 Ljava/util/Hashtable$Entry;
                       102 Ljava/util/LinkedList$Entry;
                        13 [Ljava/util/Hashtable$Entry;
                        79 Ljava/math/BigInteger;
                         2 Ljava/lang/reflect/Constructor;
                        21 [Ljava/util/concurrent/ConcurrentHashMap$HashEntry;
                         1 [Ljava/lang/Integer;
                        17 Ljava/lang/ref/Finalizer;
                         2 Ljava/util/Vector;
                        23 Lsun/security/util/DerInputBuffer;
                        23 Lsun/security/util/DerValue;
                        16 Lsun/misc/URLClassPath$JarLoader;
                         7 [Ljava/lang/Class;
                        23 Ljava/util/ArrayList;
                        21 Lsun/security/x509/AVA;
                        19 Ljava/lang/Object;
                        16 Ljava/lang/Byte;
                         5 Ljava/lang/ref/WeakReference;
                         6 [Ljava/io/ObjectStreamField;
                         9 Lsun/misc/JarIndex;
                         6 Lsun/security/x509/AlgorithmId;
                         3 [Lsun/security/x509/RDN;
                         2 Lsun/security/x509/X509CertInfo;
                         2 Lsun/security/util/MemoryCache$SoftCacheEntry;
                         2 Lsun/nio/cs/StreamEncoder;
                         6 Ljava/util/concurrent/atomic/AtomicInteger;
                         4 Ljava/util/Date;
                         1 Ljava/util/jar/JarVerifier;
                         1 [Lsun/security/jca/ProviderConfig;
                         1 Lsun/misc/Launcher$ExtClassLoader;
                         2 Lsun/security/x509/AuthorityKeyIdentifierExtension;
                         1 Ljava/lang/ThreadLocal$ThreadLocalMap;
                         1 Lsun/misc/Launcher$AppClassLoader;
                         2 Lsun/misc/URLClassPath;
                         2 Lsun/security/x509/NetscapeCertTypeExtension;
                         2 Ljava/io/OutputStreamWriter;
                         2 Ljava/security/Permissions;
                         2 Lsun/security/x509/SubjectKeyIdentifierExtension;
                         2 Lsun/security/x509/CertificateValidity;
                         1 LTest$OOMList;
                         2 Lsun/security/x509/CertificateIssuerName;
                         2 Ljava/nio/charset/CoderResult;
                         1 [Ljava/io/File;
                         2 Lsun/security/provider/DSAParameters;
                         1 [Lsun/security/x509/NetscapeCertTypeExtension$MapEntry;
                         2 Lsun/security/x509/CertificateExtensions;
                         2 Lsun/security/jca/ProviderList;
                         2 Lsun/security/x509/CertificateSubjectName;
                         1 Ljava/security/ProtectionDomain;
                         1 Ljava/io/BufferedInputStream;
                         1 Lsun/nio/cs/StandardCharsets$Aliases;
                         1 Lsun/nio/cs/StandardCharsets$Cache;
                         1 Ljava/util/IdentityHashMap;
                         1 [Lsun/security/jca/ServiceId;
                         1 Lsun/nio/cs/StandardCharsets$Classes;
                         1 Lsun/security/x509/BasicConstraintsExtension;
                         1 [Ljava/text/Normalizer$Form;
                         1 Lsun/security/x509/KeyUsageExtension;
                         2 Lsun/security/x509/CertificateVersion;
                         2 Lsun/net/www/protocol/jar/Handler;
                         2 Ljava/lang/Boolean;
                         1 Ljava/security/CodeSource;
                         1 [Ljava/lang/ThreadGroup;
                         2 Lsun/security/x509/CertificateSerialNumber;
                         1 Ljava/lang/ref/Reference;
                         1 Lsun/security/x509/SubjectAlternativeNameExtension;
                         2 Lsun/security/x509/CertificateX509Key;
                         1 Ljava/util/concurrent/atomic/AtomicReferenceFieldUpdater$AtomicReferenceFieldUpdaterImpl;
                         2 Lsun/security/x509/CertificateAlgorithmId;
                         1 Ljava/security/BasicPermissionCollection;
                         1 Lsun/misc/URLClassPath$FileLoader;
                         1 Ljava/math/MutableBigInteger;
                         1 Ljava/security/CodeSigner;
                         1 Ljava/io/FilePermissionCollection;
                         1 Ljava/util/BitSet;
                         1 Lsun/misc/Launcher$Factory;
                         1 Lsun/net/www/protocol/file/Handler;
                         1 Ljava/util/jar/JavaUtilJarAccessImpl;
                         1 Lcom/apple/java/Usage$1;
                         1 Lsun/reflect/ReflectionFactory;
                         1 Lsun/security/x509/GeneralName;
                         1 Lsun/misc/Launcher;

  12678432     396201          0 Ljava/lang/String;
   5823928        356          0 [Ljava/lang/Object;
    464552        660          0 Ljava/lang/Class;
    124248        751          0 [B
     59024        856          0 [S
     39664        788          0 [I
     16432         83          0 [Ljava/util/HashMap$Entry;
     12064        377          0 Ljava/util/HashMap$Entry;
     10720        268          0 Ljava/util/LinkedHashMap$Entry;
     10080        315          0 Ljava/util/Hashtable$Entry;
      6912        288          0 Ljava/util/LinkedList$Entry;
      4144        259          0 Ljava/lang/Integer;
      3600         75     474416 Ljava/util/HashMap;
      3280         17          0 [Ljava/util/Hashtable$Entry;
      3160         79          0 Ljava/math/BigInteger;
      2736        114          0 Lsun/security/util/ObjectIdentifier;
      2688         48          0 Ljava/security/Provider$Service;
      2560         40          0 Ljava/net/URL;
      2488         60          0 [Ljava/lang/String;
      2448        102          0 Ljava/util/LinkedList;
      2232         93          0 Ljava/security/Provider$ServiceKey;
      1920         48          0 Ljava/util/concurrent/ConcurrentHashMap$Segment;
      1584         22          0 Ljava/lang/reflect/Constructor;
      1536         48          0 Ljava/util/concurrent/locks/ReentrantLock$NonfairSync;
      1200         30          0 Ljava/lang/ref/SoftReference;
      1192         48          0 [Ljava/util/concurrent/ConcurrentHashMap$HashEntry;
      1104         46          0 Ljava/security/Provider$UString;
      1040          1          0 [Ljava/lang/Integer;
      1000         25          0 Ljava/lang/ref/Finalizer;
       992         31          0 Ljava/util/concurrent/ConcurrentHashMap$HashEntry;
       960         30          0 Ljava/security/Provider$EngineDescription;
       896         16          0 Ljava/util/jar/JarFile;
       784          7          0 Ljava/lang/Thread;
       736         23          0 Ljava/util/Vector;
       736         23          0 Lsun/security/util/DerInputBuffer;
       736         23          0 Lsun/security/util/DerValue;
       736         23          0 Lsun/security/x509/OIDMap$OIDInfo;
       672         28          0 Ljava/io/ExpiringCache$Entry;
       640         16          0 Lsun/misc/URLClassPath$JarLoader;
       640         16          0 Ljava/io/ObjectStreamField;
       608         19          0 Ljava/util/Locale;
       592          3          0 [J
       576         25          0 [Ljava/lang/Class;
       576         12          0 Ljava/util/Hashtable;
       552         23          0 Lsun/security/util/DerInputStream;
       552         23          0 Ljava/util/ArrayList;
       504         21          0 Lsun/security/x509/RDN;
       504         21          0 Lsun/security/x509/AVAKeyword;
       504         21          0 [Lsun/security/x509/AVA;
       504         21          0 Lsun/security/x509/AVA;
       440          5          0 Ljava/lang/reflect/Method;
       408         17          0 Ljava/util/jar/Attributes$Name;
       368         23          0 Ljava/lang/Object;
       352         11          0 Lsun/security/jca/ProviderConfig;
       352         11          0 Ljava/security/AccessControlContext;
       344          3          0 [Ljava/math/BigInteger;
       336          6     208576 Ljava/util/LinkedHashMap;
       336         14          0 [Ljava/lang/Byte;
       320          4          0 Ljava/util/jar/JarFile$JarFileEntry;
       312          3          0 [D
       256         16          0 Ljava/lang/Byte;
       256          8          0 Ljava/lang/ref/WeakReference;
       256          8          0 Ljava/lang/OutOfMemoryError;
       240          3          0 [Ljava/lang/ThreadLocal$ThreadLocalMap$Entry;
       240          3          0 [Ljava/util/concurrent/ConcurrentHashMap$Segment;
       240         10          0 Lsun/reflect/NativeConstructorAccessorImpl;
       224          9          0 [Ljava/io/ObjectStreamField;
       216          9          0 Lsun/misc/JarIndex;
       192          2          0 Lsun/security/provider/Sun;
       192          4          0 Lsun/security/x509/X500Name;
       192          6          0 Lsun/security/x509/AlgorithmId;
       168          7          0 Lsun/security/x509/NetscapeCertTypeExtension$MapEntry;
       160         10          0 Lsun/reflect/DelegatingConstructorAccessorImpl;
       152          4          0 [Lsun/security/x509/RDN;
       144          2          0 Ljava/lang/reflect/Field;
       144          2          0 Lsun/nio/cs/MacRoman$Encoder;
       144          2          0 Lsun/security/x509/X509CertImpl;
       144          3     751160 Ljava/util/concurrent/ConcurrentHashMap;
       128          4          0 Ljava/lang/ThreadLocal$ThreadLocalMap$Entry;
       128          4          0 Ljava/lang/ref/ReferenceQueue;
       120          5          0 Lsun/security/jca/ServiceId;
       120          5          0 Ljava/io/FileDescriptor;
       112          2          0 Lsun/security/x509/X509CertInfo;
       112          1          0 Ljava/lang/ref/Finalizer$FinalizerThread;
       112          1          0 Ljava/lang/ref/Reference$ReferenceHandler;
       112          2          0 Lsun/security/util/MemoryCache$SoftCacheEntry;
       112          2          0 Lsun/nio/cs/StreamEncoder;
       112          2          0 Ljava/io/ExpiringCache$1;
       112          4          0 [Z
        96          3          0 Ljava/util/zip/Inflater;
        96          2          0 Ljava/nio/HeapByteBuffer;
        96          6          0 Ljava/lang/ref/ReferenceQueue$Lock;
        96          3          0 Ljava/io/FileInputStream;
        96          4          0 Ljava/io/File;
        96          1          0 Lsun/security/jca/ProviderList$1;
        96          2          0 Ljava/lang/ThreadGroup;
        96          2          0 Ljava/io/BufferedWriter;
        96          6          0 Ljava/util/concurrent/atomic/AtomicInteger;
        96          3          0 Ljava/util/Stack;
        96          4          0 Ljava/util/Date;
        96          2          0 Ljava/util/Properties;
        96          4          0 Ljava/text/Normalizer$Form;
        88          1          0 [[Ljava/lang/Byte;
        88          1          0 [Lsun/security/util/ObjectIdentifier;
        88          1          0 Ljava/util/jar/JarVerifier;
        80          1          0 [[B
        80          2          0 Lsun/security/provider/DSAPublicKeyImpl;
        80          2          0 Ljava/io/ExpiringCache;
        80          2          0 [Lsun/security/jca/ProviderConfig;
        80          1          0 Lsun/misc/Launcher$ExtClassLoader;
        80          5          0 Ljava/lang/ThreadLocal;
        80          2          0 Lsun/security/x509/AuthorityKeyIdentifierExtension;
        72          3          0 Ljava/lang/ThreadLocal$ThreadLocalMap;
        72          3          0 Lsun/misc/Signal;
        72          3          0 Ljava/util/zip/ZStreamRef;
        72          3          0 Ljava/lang/RuntimePermission;
        72          1          0 Lsun/misc/Launcher$AppClassLoader;
        64          1          0 [F
        64          2          0 Lsun/misc/URLClassPath;
        64          2          0 Ljava/security/AlgorithmParameters;
        64          1          0 Lsun/security/provider/NativePRNG$RandomIO;
        64          2          0 Lsun/security/x509/NetscapeCertTypeExtension;
        64          2          0 Ljava/io/OutputStreamWriter;
        64          4          0 Lsun/security/x509/KeyIdentifier;
        64          2          0 Lsun/security/util/MemoryCache;
        64          4          0 Ljava/util/HashMap$EntrySet;
        64          2          0 Ljava/io/PrintStream;
        64          2          0 Ljava/lang/ref/ReferenceQueue$Null;
        64          2          0 Ljava/io/FileOutputStream;
        64          2          0 Ljava/security/Permissions;
        64          2          0 [Ljava/lang/Thread;
        64          2          0 Lsun/security/x509/SubjectKeyIdentifierExtension;
        56          1          0 [Ljava/lang/Runnable;
        48          2          0 Lsun/security/x509/CertificateValidity;
        48          2   50776680 LTest$OOMList;
        48          2          0 Lsun/security/x509/CertificateIssuerName;
        48          2          0 Ljava/nio/charset/CoderResult;
        48          3          0 Lsun/text/normalizer/NormalizerBase$QuickCheckResult;
        48          2          0 Lsun/misc/NativeSignalHandler;
        48          2          0 [Ljava/io/File;
        48          2          0 Lsun/security/provider/DSAParameters;
        48          2          0 Ljava/io/BufferedOutputStream;
        48          1          0 [Lsun/security/x509/NetscapeCertTypeExtension$MapEntry;
        48          2          0 Lsun/security/x509/CertificateExtensions;
        48          2          0 Lsun/security/util/BitArray;
        48          2          0 Lsun/security/jca/ProviderList;
        48          2          0 Lsun/security/x509/CertificateSubjectName;
        48          2          0 Lsun/nio/cs/Surrogate$Parser;
        48          3          0 Ljava/nio/charset/CodingErrorAction;
        48          2          0 Lsun/security/jca/ProviderList$3;
        48          2          0 Lsun/security/util/Cache$EqualByteArray;
        40          1          0 Ljava/security/ProtectionDomain;
        40          2          0 [Ljava/security/CodeSigner;
        40          1          0 Ljava/io/BufferedInputStream;
        40          1          0 Lsun/nio/cs/StandardCharsets$Aliases;
        40          1          0 Lsun/nio/cs/StandardCharsets$Cache;
        40          1      27544 Ljava/util/IdentityHashMap;
        40          1          0 [Lsun/security/jca/ServiceId;
        40          1          0 Lsun/nio/cs/StandardCharsets$Classes;
        32          1          0 Ljava/lang/VirtualMachineError;
        32          1          0 Ljava/util/Collections$SynchronizedMap;
        32          1          0 [Ljava/lang/OutOfMemoryError;
        32          1          0 Lsun/security/x509/BasicConstraintsExtension;
        32          1          0 [Ljava/text/Normalizer$Form;
        32          2          0 Lsun/security/x509/SerialNumber;
        32          1          0 Ljava/lang/NullPointerException;
        32          1          0 Lsun/security/x509/KeyUsageExtension;
        32          1          0 Lsun/misc/SoftCache;
        32          2          0 Lsun/security/x509/CertificateVersion;
        32          2          0 Lsun/net/www/protocol/jar/Handler;
        32          2          0 Ljava/lang/Boolean;
        32          2          0 Ljava/lang/Shutdown$Lock;
        32          1          0 Ljava/security/CodeSource;
        32          1          0 [Ljava/lang/ThreadGroup;
        32          2          0 Lsun/security/x509/CertificateSerialNumber;
        32          1          0 Ljava/lang/ref/Reference;
        32          1          0 Ljava/io/UnixFileSystem;
        32          1          0 Lsun/security/x509/SubjectAlternativeNameExtension;
        32          1          0 Ljava/lang/ArithmeticException;
        32          1          0 Ljava/lang/ClassLoader$NativeLibrary;
        32          1          0 Ljava/io/FilePermission;
        32          2          0 Lsun/security/x509/CertificateX509Key;
        32          2          0 Ljava/util/HashSet;
        32          1          0 Ljava/util/concurrent/atomic/AtomicReferenceFieldUpdater$AtomicReferenceFieldUpdaterImpl;
        32          1          0 Lsun/nio/cs/StandardCharsets;
        32          2          0 Lsun/security/x509/CertificateAlgorithmId;
        32          2          0 Ljava/nio/ByteOrder;
        32          1          0 Ljava/security/BasicPermissionCollection;
        24          1          0 Lcom/apple/java/Usage;
        24          1          0 Ljava/lang/reflect/ReflectPermission;
        24          1          0 Lsun/misc/URLClassPath$FileLoader;
        24          1          0 Ljava/util/Collections$UnmodifiableRandomAccessList;
        24          1          0 Lsun/nio/cs/US_ASCII;
        24          1          0 Ljava/math/MutableBigInteger;
        24          1          0 Ljava/util/Collections$EmptyMap;
        24          1          0 Lsun/security/provider/certpath/X509CertPath;
        24          1          0 Ljava/security/Policy$UnsupportedEmptyCollection;
        24          1          0 Ljava/security/CodeSigner;
        24          1          0 Lsun/nio/cs/UTF_8;
        24          1          0 Ljava/io/FilePermissionCollection;
        24          1          0 Ljava/lang/StringBuilder;
        24          1          0 Ljava/util/Arrays$ArrayList;
        24          1          0 Lsun/nio/cs/MacRoman;
        24          1          0 Ljava/util/BitSet;
        16          1          0 [Ljava/security/Provider;
        16          1          0 Lsun/jkernel/DownloadManager$1;
        16          1          0 Lsun/text/normalizer/NormalizerBase$NFKCMode;
        16          1          0 Lsun/misc/Launcher$Factory;
        16          1          0 Ljava/nio/charset/CoderResult$2;
        16          1          0 Lsun/net/www/protocol/file/Handler;
        16          1          0 Ljava/util/jar/JavaUtilJarAccessImpl;
        16          1          0 Ljava/lang/System$2;
        16          1          0 Ljava/lang/reflect/ReflectAccess;
        16          1          0 Lsun/misc/FloatingDecimal$1;
        16          1          0 Ljava/util/jar/JarVerifier$3;
        16          1          0 Lsun/text/normalizer/NormalizerBase$Mode;
        16          1          0 Ljava/util/Collections$EmptySet;
        16          1          0 Ljava/util/Hashtable$EmptyEnumerator;
        16          1          0 Lsun/misc/ASCIICaseInsensitiveComparator;
        16          1          0 [Ljava/security/cert/Certificate;
        16          1          0 Ljava/security/ProtectionDomain$Key;
        16          1          0 Lcom/apple/java/Usage$1;
        16          1          0 Ljava/lang/Runtime;
        16          1          0 Ljava/security/AccessControlContext$1;
        16          1          0 [Ljava/lang/StackTraceElement;
        16          1          0 Lsun/text/normalizer/NormalizerBase$NFDMode;
        16          1          0 Ljava/util/Collections$UnmodifiableCollection;
        16          1          0 Ljava/util/Collections$EmptyList;
        16          1          0 Ljava/lang/InheritableThreadLocal;
        16          1          0 Ljava/nio/charset/CoderResult$1;
        16          1          0 Lsun/security/x509/RFC822Name;
        16          1          0 Lsun/reflect/ReflectionFactory;
        16          1          0 Ljava/lang/Terminator$1;
        16          1          0 Ljava/lang/ApplicationShutdownHooks$1;
        16          1          0 Lsun/security/util/ByteArrayLexOrder;
        16          1          0 Ljava/net/URLClassLoader$7;
        16          1          0 [Ljava/security/Principal;
        16          1          0 Lsun/security/util/ByteArrayTagOrder;
        16          1          0 Lsun/security/x509/GeneralName;
        16          1          0 Ljava/util/regex/Pattern$5;
        16          1          0 Ljava/lang/String$CaseInsensitiveComparator;
        16          1          0 Lsun/util/calendar/Gregorian;
        16          1          0 Lsun/security/x509/GeneralNames;
        16          1          0 Lsun/misc/Launcher;
        16          1          0 Ljava/util/regex/Pattern$Node;
        16          1          0 Ljava/lang/ref/Reference$Lock;
        16          1          0 Lsun/text/normalizer/NormalizerBase$NFCMode;
        16          1          0 Ljava/util/Collections$ReverseComparator;
        16          1          0 Lsun/misc/Unsafe;
        16          1          0 Lsun/text/normalizer/NormalizerBase$NFKDMode;
        16          1          0 Ljava/util/Hashtable$EmptyIterator;
        16          1          0 Ljava/security/ProtectionDomain$2;
        16          1          0 Ljava/net/UnknownContentHandler;
        16          1          0 Ljava/io/FileDescriptor$1;
        16          1          0 Ljava/util/regex/Pattern$LastNode;
---------- ---------- ----------------------

Resuming threads.
Printing thread dump.

Dumping thread state for 4 threads

#1 - Signal Dispatcher - RUNNABLE

#2 - Finalizer - WAITING
        at java.lang.Object.wait(Object.java)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:118)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:134)
        at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:159)

#3 - Reference Handler - WAITING
        at java.lang.Object.wait(Object.java)
        at java.lang.Object.wait(Object.java:485)
        at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:116)

#4 - main - RUNNABLE - [OOM thrower]
        at java.lang.StringBuilder.toString(StringBuilder.java:430)
        at Test.main(Test.java:16)

License

Polarbear is based on Sun Microsystems sample JVMTI code, and follows the license rules issued by Sun. All modifications are released under the same license.

Polarbear?

If you were a fan of LOST, you may understand why "Out of memory" and polar bears are related thoughts for us.