jstack jmap jstat
代码，这里以这个为例怎样使用jstack诊断Java应用程序故障
public class DeadLock {
public static void main(String[] args) {
final Object obj_1 = new Object(), obj_2 = new Object();
Thread t1 = new Thread("t1"){
@Override
public void run() {
synchronized (obj_1) {
try {
Thread.sleep(3000);
} catch (InterruptedException e) {}
synchronized (obj_2) {
System.out.println("thread t1 done.");
}
}
}
};
Thread t2 = new Thread("t2"){
@Override
public void run() {
synchronized (obj_2) {
try {
Thread.sleep(3000);
} catch (InterruptedException e) {}
synchronized (obj_1) {
System.out.println("thread t2 done.");
}
}
}
};
t1.start();
t2.start();
}
}
jstack 死锁问题
root@ubuntu:~# jstack 5606
2015-01-24 13:45:07
Full thread dump Java HotSpot(TM) 64-Bit Server VM (23.7-b01 mixed mode):
"Attach Listener" daemon prio=10 tid=0x0000000001441800 nid=0x165d waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"DestroyJavaVM" prio=10 tid=0x00007f435007b000 nid=0x15e7 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"t2" prio=10 tid=0x00007f4350079000 nid=0x15f5 waiting for monitor entry [0x00007f4356b5d000]
java.lang.Thread.State: BLOCKED (on object monitor)
at DeadLock$2.run(DeadLock.java:30)
- waiting to lock <0x0000000085800808> (a java.lang.Object)
- locked <0x0000000085800818> (a java.lang.Object)
"t1" prio=10 tid=0x00007f4350077000 nid=0x15f4 waiting for monitor entry [0x00007f4356c5e000]
java.lang.Thread.State: BLOCKED (on object monitor)
at DeadLock$1.run(DeadLock.java:15)
- waiting to lock <0x0000000085800818> (a java.lang.Object)
- locked <0x0000000085800808> (a java.lang.Object)
"Service Thread" daemon prio=10 tid=0x00007f4350056000 nid=0x15f2 runnable [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C2 CompilerThread1" daemon prio=10 tid=0x00007f4350053000 nid=0x15f1 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C2 CompilerThread0" daemon prio=10 tid=0x00007f4350050000 nid=0x15f0 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"Signal Dispatcher" daemon prio=10 tid=0x00007f435004e000 nid=0x15ef runnable [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"Finalizer" daemon prio=10 tid=0x00007f4350001000 nid=0x15ee in Object.wait() [0x00007f4357739000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x0000000085808120> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:135)
- locked <0x0000000085808120> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:151)
at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:177)
"Reference Handler" daemon prio=10 tid=0x00000000014d2000 nid=0x15ed in Object.wait() [0x00007f435783a000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x00000000858006b8> (a java.lang.ref.Reference$Lock)
at java.lang.Object.wait(Object.java:503)
at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:133)
- locked <0x00000000858006b8> (a java.lang.ref.Reference$Lock)
"VM Thread" prio=10 tid=0x00000000014ca800 nid=0x15ec runnable
"GC task thread#0 (ParallelGC)" prio=10 tid=0x000000000144f000 nid=0x15e8 runnable
"GC task thread#1 (ParallelGC)" prio=10 tid=0x0000000001451000 nid=0x15e9 runnable
"GC task thread#2 (ParallelGC)" prio=10 tid=0x0000000001453000 nid=0x15ea runnable
"GC task thread#3 (ParallelGC)" prio=10 tid=0x0000000001455000 nid=0x15eb runnable
"VM Periodic Task Thread" prio=10 tid=0x00007f4350068800 nid=0x15f3 waiting on condition
JNI global references: 111
Found one Java-level deadlock:
=============================
"t2":
waiting to lock monitor 0x00000000014d9600 (object 0x0000000085800808, a java.lang.Object),
which is held by "t1"
"t1":
waiting to lock monitor 0x00000000014d8250 (object 0x0000000085800818, a java.lang.Object),
which is held by "t2"
Java stack information for the threads listed above:
===================================================
"t2":
at DeadLock$2.run(DeadLock.java:30)
- waiting to lock <0x0000000085800808> (a java.lang.Object)
- locked <0x0000000085800818> (a java.lang.Object)
"t1":
at DeadLock$1.run(DeadLock.java:15)
- waiting to lock <0x0000000085800818> (a java.lang.Object)
- locked <0x0000000085800808> (a java.lang.Object)
Found 1 deadlock.
jmap
jmap -dump:live,format=b,file=jmapfile 5606
jhat -J-Xmx1024M jmapfile,可以通过http://ip:7000查看
instance 数量 http://172.16.10.187:7000/histo/
root@ubuntu:~# jhat -J-Xmx1024M jmapfile
Reading from jmapfile...
Dump file created Sat Jan 24 11:39:28 CST 2015
Snapshot read, resolving...
Resolving 4839 objects...
Chasing references, expect 0 dots
Eliminating duplicate references
Snapshot resolved.
Started HTTP server on port 7000
Server is ready.
也可以直接
jmap -histo 5606
root@ubuntu:~# jmap -histo 5606
num #instances #bytes class name
----------------------------------------------
1: 344 1305352 [I
2: 5315 727592 <methodKlass>
3: 5315 640880 <constMethodKlass>
4: 356 407288 <constantPoolKlass>
5: 322 257216 <constantPoolCacheKlass>
6: 356 255536 <instanceKlassKlass>
7: 428 81568 [B
8: 879 76496 [C
9: 416 50712 java.lang.Class
10: 573 37152 [[I
11: 536 33704 [S
12: 43 24768 <objArrayKlassKlass>
13: 858 20592 java.lang.String
14: 312 13144 [Ljava.lang.Object;
15: 107 7704 java.lang.reflect.Field
16: 8 4608 <typeArrayKlassKlass>
17: 108 3456 java.util.Hashtable$Entry
18: 11 2288 <klassKlass>
19: 52 1904 [Ljava.lang.String;
20: 38 1824 sun.util.locale.LocaleObjectCache$CacheEntry
21: 55 1760 java.util.concurrent.ConcurrentHashMap$HashEntry
22: 40 1600 java.util.concurrent.ConcurrentHashMap$Segment
23: 16 1344 [Ljava.util.HashMap$Entry;
24: 40 1280 java.util.concurrent.locks.ReentrantLock$NonfairSync
25: 40 1088 [Ljava.util.concurrent.ConcurrentHashMap$HashEntry;
26: 16 1024 java.net.URL
27: 6 992 [Ljava.util.Hashtable$Entry;
28: 14 784 java.util.HashMap
29: 19 760 java.io.ObjectStreamField
30: 19 760 sun.util.locale.BaseLocale$Key
jstat
-class： 统计class loader 行为信息
-compiler： 统计编译行为信息
-gc：统计jdk gc时heap信息
-gccapacity：统计不同的generations（新生代、老生代、永久代）相应的heap容量信息
-gccause：统计gc的情况，以及引起gc的事情。同-gcutil
-gcnew：统计新生代的gc情况
-gcnewcapacity：统计新生代gc时heap的容量信息
-gcold：统计老生代的gc情况
-gcoldcapacity：统计老生代gc时heap容量信息
-gcpermcapacity：统计永久代gc时的容量信息
-gcutil：统计heap的gc情况
-printcompilation：
jstat -gcutil 5606 100 10
root@ubuntu:~# jstat -gcutil 5606 100 10
S0 S1 E O P YGC YGCT FGC FGCT GCT
0.00 0.00 4.00 0.71 11.33 1 0.001 1 0.007 0.008
0.00 0.00 4.00 0.71 11.33 1 0.001 1 0.007 0.008
0.00 0.00 4.00 0.71 11.33 1 0.001 1 0.007 0.008
0.00 0.00 4.00 0.71 11.33 1 0.001 1 0.007 0.008
0.00 0.00 4.00 0.71 11.33 1 0.001 1 0.007 0.008
0.00 0.00 4.00 0.71 11.33 1 0.001 1 0.007 0.008
0.00 0.00 4.00 0.71 11.33 1 0.001 1 0.007 0.008
0.00 0.00 4.00 0.71 11.33 1 0.001 1 0.007 0.008
0.00 0.00 4.00 0.71 11.33 1 0.001 1 0.007 0.008
0.00 0.00 4.00 0.71 11.33 1 0.001 1 0.007 0.008
结果信息：
S0 — Heap上的 Survivor space 0 区已使用空间的百分比
S1 — Heap上的 Survivor space 1 区已使用空间的百分比
E — Heap上的 Eden space 区已使用空间的百分比
O — Heap上的 Old space 区已使用空间的百分比
P — Perm space 区已使用空间的百分比
YGC — 从应用程序启动到采样时发生 Young GC 的次数
YGCT– 从应用程序启动到采样时 Young GC 所用的时间(单位秒)
FGC — 从应用程序启动到采样时发生 Full GC 的次数
FGCT– 从应用程序启动到采样时 Full GC 所用的时间(单位秒)
GCT — 从应用程序启动到采样时用于垃圾回收的总时间(单位秒)
jstat -gccapacity 3851 1000 10
root@ubuntu:~# jstat -gccapacity 5606 1000 10
NGCMN NGCMX NGC S0C S1C EC OGCMN OGCMX OGC OC PGCMN PGCMX PGC PC YGC FGC
41792.0 668992.0 41792.0 5184.0 5184.0 31424.0 83648.0 1338048.0 31680.0 31680.0 21248.0 83968.0 21248.0 21248.0 1 1
41792.0 668992.0 41792.0 5184.0 5184.0 31424.0 83648.0 1338048.0 31680.0 31680.0 21248.0 83968.0 21248.0 21248.0 1 1
41792.0 668992.0 41792.0 5184.0 5184.0 31424.0 83648.0 1338048.0 31680.0 31680.0 21248.0 83968.0 21248.0 21248.0 1 1
41792.0 668992.0 41792.0 5184.0 5184.0 31424.0 83648.0 1338048.0 31680.0 31680.0 21248.0 83968.0 21248.0 21248.0 1 1
41792.0 668992.0 41792.0 5184.0 5184.0 31424.0 83648.0 1338048.0 31680.0 31680.0 21248.0 83968.0 21248.0 21248.0 1 1
41792.0 668992.0 41792.0 5184.0 5184.0 31424.0 83648.0 1338048.0 31680.0 31680.0 21248.0 83968.0 21248.0 21248.0 1 1
41792.0 668992.0 41792.0 5184.0 5184.0 31424.0 83648.0 1338048.0 31680.0 31680.0 21248.0 83968.0 21248.0 21248.0 1 1
41792.0 668992.0 41792.0 5184.0 5184.0 31424.0 83648.0 1338048.0 31680.0 31680.0 21248.0 83968.0 21248.0 21248.0 1 1
41792.0 668992.0 41792.0 5184.0 5184.0 31424.0 83648.0 1338048.0 31680.0 31680.0 21248.0 83968.0 21248.0 21248.0 1 1
41792.0 668992.0 41792.0 5184.0 5184.0 31424.0 83648.0 1338048.0 31680.0 31680.0 21248.0 83968.0 21248.0 21248.0 1 1