The following are examples of running the j_calls.d script. This traces activity from all Java processes on the system with hotspot provider support (1.6.0). Method calls and object allocation are only visible when using the flag "+ExtendedDTraceProbes". eg, java -XX:+ExtendedDTraceProbes classfile Here we see it running on Code/Java/Func_abc # j_calls.d Tracing... Hit Ctrl-C to end. ^C PID TYPE NAME COUNT 311334 cload Func_abc 1 311334 cload java/io/BufferedInputStream 1 311334 cload java/io/BufferedOutputStream 1 311334 cload java/io/BufferedReader 1 311334 cload java/io/BufferedWriter 1 311334 cload java/io/Closeable 1 311334 cload java/io/Console 1 311334 cload java/io/Console$1 1 311334 cload java/io/Console$1$1 1 311334 cload java/io/DataInput 1 311334 cload java/io/DataInputStream 1 311334 cload java/io/DeleteOnExitHook 1 311334 cload java/io/ExpiringCache 1 311334 cload java/io/ExpiringCache$1 1 311334 cload java/io/ExpiringCache$Entry 1 311334 cload java/io/File 1 311334 cload java/io/File$1 1 311334 cload java/io/FileDescriptor 1 311334 cload java/io/FileInputStream 1 311334 cload java/io/FileOutputStream 1 311334 cload java/io/FilePermission 1 311334 cload java/io/FilePermission$1 1 311334 cload java/io/FilePermissionCollection 1 311334 cload java/io/FileReader 1 311334 cload java/io/FileSystem 1 311334 cload java/io/FilterInputStream 1 311334 cload java/io/FilterOutputStream 1 311334 cload java/io/Flushable 1 311334 cload java/io/InputStream 1 311334 cload java/io/InputStreamReader 1 311334 cload java/io/ObjectStreamClass 1 311334 cload java/io/ObjectStreamField 1 311334 cload java/io/OutputStream 1 311334 cload java/io/OutputStreamWriter 1 311334 cload java/io/PrintStream 1 311334 cload java/io/Reader 1 311334 cload java/io/Serializable 1 311334 cload java/io/UnixFileSystem 1 311334 cload java/io/Writer 1 311334 cload java/lang/AbstractStringBuilder 1 311334 cload java/lang/Appendable 1 311334 cload java/lang/ApplicationShutdownHooks 1 311334 cload java/lang/ArithmeticException 1 311334 cload java/lang/ArrayStoreException 1 311334 cload java/lang/Boolean 1 311334 cload java/lang/Byte 1 311334 cload java/lang/CharSequence 1 311334 cload java/lang/Character 1 311334 cload java/lang/CharacterDataLatin1 1 311334 cload java/lang/Class 1 [... 1400 lines truncated ...] 311334 method java/lang/Class.getClassLoader0 34 311334 method java/lang/String.toLowerCase 34 311334 method sun/security/action/GetPropertyAction.run 34 311334 method java/nio/CharBuffer.arrayOffset 36 311334 method java/util/HashMap.getEntry 36 311334 method java/io/File. 37 311334 method java/io/UnixFileSystem.prefixLength 37 311334 oalloc java/io/File 37 311334 oalloc java/lang/reflect/Field 37 311334 method java/io/BufferedReader.readLine 38 311334 method java/util/concurrent/locks/AbstractOwnableSynchronizer.setExclusiveOwnerThread 38 311334 method java/lang/CharacterDataLatin1.toLowerCase 41 311334 method java/lang/CharacterDataLatin1.getProperties 43 311334 method java/security/AccessController.doPrivileged 43 311334 method java/util/Vector.size 43 311334 method java/nio/Buffer.position 44 311334 method java/nio/ByteBuffer.arrayOffset 44 311334 method java/lang/System.getProperty 48 311334 method java/util/Properties.getProperty 50 311334 method java/util/BitSet.expandTo 51 311334 method java/util/BitSet.set 51 311334 method java/lang/System.checkKey 56 311334 method java/lang/Thread.currentThread 57 311334 method java/util/Hashtable$Entry. 57 311334 oalloc [Ljava/lang/String; 57 311334 oalloc java/util/Hashtable$Entry 57 311334 method java/util/Hashtable.get 59 311334 method java/util/Hashtable.put 63 311334 method java/util/BitSet.checkInvariants 71 311334 method java/util/BitSet.wordIndex 72 311334 method java/lang/StringBuilder. 73 311334 method java/lang/StringBuilder.toString 73 311334 oalloc java/lang/StringBuilder 73 311334 method java/lang/AbstractStringBuilder.expandCapacity 81 311334 method java/util/HashMap.hash 81 311334 method java/util/HashMap.indexFor 81 311334 method java/lang/AbstractStringBuilder. 82 311334 method java/lang/Character.toLowerCase 82 311334 method java/lang/String.startsWith 83 311334 method java/util/Arrays.copyOf 87 311334 method java/lang/String.lastIndexOf 90 311334 method java/lang/String.substring 94 311334 method java/util/Arrays.copyOfRange 107 311334 method java/lang/String.getChars 156 311334 method java/lang/System.getSecurityManager 174 311334 method java/lang/String. 175 311334 method java/lang/String.equals 202 311334 method java/lang/Math.min 208 311334 method java/lang/String.hashCode 213 311334 method java/lang/String.indexOf 302 311334 oalloc [Ljava/lang/Object; 326 311334 method java/lang/System.arraycopy 360 311334 oalloc [I 374 311334 oalloc java/lang/Class 395 311334 oalloc [B 406 311334 oalloc [S 486 311334 method java/lang/StringBuilder.append 533 311334 oalloc [[I 541 311334 method java/lang/AbstractStringBuilder.append 549 311334 method java/lang/Object. 823 311334 oalloc java/lang/String 931 311334 oalloc [C 1076 311334 method java/lang/String.charAt 1960 This shows us each of the events associated with the PID 311334, and the number of times each event happened. These events can be of type cload (class load), method (method call), mcompile (method compile), mload (compiled method load), oalloc (object alloc) or thread (thread start). In this case you can see 1960 calls to java/lang/String.charAt, and 1076 object allocations of type [C.