Solve the attach PID error of JDK tools such as jmap in ubuntu11.10

1. Error Cases

nathan@ubuntu:~/Downloads$ jmap -heap 3991Attaching to process ID 3991, please wait...Error attaching to process: sun.jvm.hotspot.debugger.DebuggerException: Can't attach to the process

2. Solution

1) modify the/etc/sysctl. d/10-ptrace.conf file as follows:

< kernel.yama.ptrace_scope = 1---> kernel.yama.ptrace_scope = 0
(Change 1 to 0)
2) Restart
3. Successful
nathan@ubuntu:~$ jmap -heap 1835Attaching to process ID 1835, please wait...Debugger attached successfully.Client compiler detected.JVM version is 20.0-b11using thread-local object allocation.Mark Sweep Compact GCHeap Configuration:   MinHeapFreeRatio = 40   MaxHeapFreeRatio = 70   MaxHeapSize      = 402653184 (384.0MB)   NewSize          = 1048576 (1.0MB)   MaxNewSize       = 4294901760 (4095.9375MB)   OldSize          = 4194304 (4.0MB)   NewRatio         = 2   SurvivorRatio    = 8   PermSize         = 12582912 (12.0MB)   MaxPermSize      = 268435456 (256.0MB)Heap Usage:New Generation (Eden + 1 Survivor Space):   capacity = 13697024 (13.0625MB)   used     = 6592008 (6.286628723144531MB)   free     = 7105016 (6.775871276855469MB)   48.12730122981459% usedEden Space:   capacity = 12189696 (11.625MB)   used     = 6592008 (6.286628723144531MB)   free     = 5597688 (5.338371276855469MB)   54.07852665070565% usedFrom Space:   capacity = 1507328 (1.4375MB)   used     = 0 (0.0MB)   free     = 1507328 (1.4375MB)   0.0% usedTo Space:   capacity = 1507328 (1.4375MB)   used     = 0 (0.0MB)   free     = 1507328 (1.4375MB)   0.0% usedtenured generation:   capacity = 30273536 (28.87109375MB)   used     = 18162752 (17.32135009765625MB)   free     = 12110784 (11.54974365234375MB)   59.995475916655394% usedPerm Generation:   capacity = 38273024 (36.5MB)   used     = 38107752 (36.342384338378906MB)   free     = 165272 (0.15761566162109375MB)   99.56817626953125% used
4. Reference http://bugs.sun.com/bugdatabase/view_bug.do? Bug_id = 7050524