Matty's email at 10/12/2007 9:49 PM, said: > Howdy, > > I am trying to use the Java 6 hotspot provider's object-alloc probe to > determine where objects are being allocated in an application. When I > use the attached DTrace script [1], I keep seeing unresolved symbols > and "couldn't find start" errors in the output: > > libjvm.so`__1cNSharedRuntimeYdtrace_object_alloc_base6FpnGThread_pnHoopDesc__i_+0x7d > > libjvm.so`__1cNSharedRuntimeTdtrace_object_alloc6FpnHoopDesc__i_+0x4f > > libjvm.so`__1cNCollectedHeapbCpost_allocation_setup_common6FnLKlassHandle_pnIHeapWord_I_v_+0x121 > > libjvm.so`__1cOtypeArrayKlassIallocate6MipnGThread__pnQtypeArrayOopDesc__+0x19b > > libjvm.so`__1cKoopFactoryNnew_typeArray6FnJBasicType_ipnGThread__pnQtypeArrayOopDesc__+0x2f > > libjvm.so`__1cSInterpreterRuntimeInewarray6FpnKJavaThread_nJBasicType_i_v_+0x33 > <couldn't find start> > java/nio/ByteBuffer.allocate(I)Ljava/nio/ByteBuffer; > > sun/nio/cs/StreamDecoder.<init>(Ljava/io/InputStream;Ljava/lang/Object;Ljava/nio/charset/CharsetDecoder;)V > > sun/nio/cs/StreamDecoder.<init>(Ljava/io/InputStream;Ljava/lang/Object;Ljava/nio/charset/Charset;)V > > sun/nio/cs/StreamDecoder.forInputStreamReader(Ljava/io/InputStream;Ljava/lang/Object;Ljava/lang/String;)Lsun/nio/cs/StreamDecoder; > 0xfb402da7 > 0xfb402f0d > 0xfb402f0d > 0xfb402f0d > 0xfb402da7 > 0xfb402da7 > 0xfb66e4d4 > 0xf7308980 > 4448736 > > Does anyone happen to know what is going on here? Without the method > names leading up to the actual allocations, it is somewhat difficult > to pinpoint who is keeping the garbage collector busy. > > Thanks for any insight, > - Ryan
The default buffer size passed the the Java helper is too small. Change your jstack() to be something like: jstack(40,1024) This gives a 1024 byte buffer. I would not make it arbitrarily large, but I have never needed more than 2048 in the hundreds of times I have looked at Java apps. That should help you be able to resolve all of the symbols (well actually, they are all resolved - just nowhere to put them). Thanks, Jarod _______________________________________________ dtrace-discuss mailing list [email protected]
