本文介绍了为什么java newInstance挂在getDeclaredConstructors0上？的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我们使用mozlia rhino生成动态类，然后通过这样的自定义类加载器加载JsClass
We use mozlia rhino to generate dynamic class, then load JsClass by custom classloader like this
DynamicClassLoader loader = new DynamicClassLoader(JavaScriptFactory.class.getClassLoader());
Class<?> jsClass = loader.loadClass("D://","com.huawei.xxx");
jsClass.newInstance();
如您所见，每个JsClass都有一个单独的类加载器，当用户修改js时，我们还将重新加载JsClass通过此代码，
As you see, every JsClass have a seperate classloader, when user modify js, we will also reload JsClass by this code,
现在，我们面临一个问题，当调用jsClass.newInstance（）时，一些线程在getDeclaredConstructors0上挂了很长时间（3s-1000s），通常应该少于10ms。有人可以告诉我可能的原因吗？非常感谢！
Now, we face a problem, when call jsClass.newInstance(), some thread hang at getDeclaredConstructors0 for a long time(3s-1000s), normally it shoud be less then 10ms. Can someone tell me the possiable reason? Thanks very much!
JDK：
1.8.0.60
JDK:1.8.0.60
Tomcat：
7.0.59
Tomcat:7.0.59
JvmArgs：
-Dnop -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -DDN=mateinfo_app -server -Duser.timezone=GMT -Dsun.rmi.dgc.client.gcInterval=3600000 -Dsun.rmi.dgc.server.gcInterval=3600000 -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyFraction=80 -XX:+DisableExplicitGC -XX:+PrintGC -XX:+PrintGCDateStamps -XX:+PrintHeapAtGC -XX:+PrintGCDetails -Xloggc:/opt/mateinfo/logs/app/tomcat-gc-20160601-233343.log -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/opt/mateinfo/logs/app/oom-20160601-233343.bin -XX:OnOutOfMemoryError=./deal-oom.sh -Xms3260m -Xmx3260m -Xmn800m -XX:MetaspaceSize=800m -XX:MaxMetaspaceSize=800m -XX:SurvivorRatio=16 -XX:+OptimizeStringConcat -Xverify:all -Dsoapui.log4j.config=/opt/mateinfo/app/lib/log4j.properties -Dlog4j.ignoreTCL=true -XX:-OmitStackTraceInFastThrow -Xrunjdwp:transport=dt_socket,address=8000,server=y,suspend=n -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.port=8050 -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.authenticate=false -Djava.net.preferIPv4Stack=true -Djava.endorsed.dirs=/opt/mateinfo/app/endorsed -classpath /opt/mateinfo/app/bin/bootstrap.jar:/opt/mateinfo/app/bin/tomcat-juli.jar -Dcatalina.base=/opt/mateinfo/app -Dcatalina.home=/opt/mateinfo/app -Djava.io.tmpdir=/opt/mateinfo/app/temp org.apache.catalina.startup.Bootstrap start
线程转储：
----------------- 7123 -----------------
0x00007f9d44cdc6d5 __pthread_cond_wait + 0xc5
0x00007f9d43cc157c _ZN15JvmtiRawMonitor11SimpleEnterEP6Thread + 0xdc
0x00007f9d43cc1c07 _ZN15JvmtiRawMonitor9raw_enterEP6Thread + 0xd7
0x00007f9d43c9a2ed _ZN8JvmtiEnv15RawMonitorEnterEP15JvmtiRawMonitor + 0xad
0x00007f9d429c4df8 debugMonitorEnter + 0x38
0x00007f9d429b1451 event_callback + 0x2e1
0x00007f9d429b1e8e cbClassPrepare + 0x8e
0x00007f9d43cb0beb _ZN11JvmtiExport18post_class_prepareEP10JavaThreadP5Klass + 0x15b
0x00007f9d43b59f31 _ZN13InstanceKlass15link_class_implE19instanceKlassHandlebP6Thread + 0x3f1
0x00007f9d43b5a0d4 _ZN13InstanceKlass10link_classEP6Thread + 0x54
0x00007f9d43c3ec49 _ZL33get_class_declared_methods_helperP7JNIEnv_P7_jclasshbP5KlassP6Thread + 0xc9
0x00007f9d43c3f28e JVM_GetClassDeclaredConstructors + 0xce
"app-JavaScriptFactory-7-thread-1" #41621 prio=5 os_prio=0 tid=0x00007f9d1d7f9800 nid=0x1bd3 runnable [0x00007f9c8040e000]
java.lang.Thread.State: RUNNABLE
at java.lang.Class.getDeclaredConstructors0(Native Method)
at java.lang.Class.privateGetDeclaredConstructors(Class.java:2671)
at java.lang.Class.getConstructor0(Class.java:3075)
at java.lang.Class.newInstance(Class.java:412)
at com.huawei.sdm.integration.message.runtime.handler.script.JsBeanGenerateRunner.excute(JsBeanGenerateRunner.java:82)
at com.huawei.mateinfo.context.support.CommonCallable.call(CommonCallable.java:31)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
GCLog：
{Heap before GC invocations=331320 (full 1587):
par new generation total 773696K, used 732120K [0x00000006f4400000, 0x0000000726400000, 0x0000000726400000)
eden space 728192K, 100% used [0x00000006f4400000, 0x0000000720b20000, 0x0000000720b20000)
from space 45504K, 8% used [0x0000000723790000, 0x0000000723b66170, 0x0000000726400000)
to space 45504K, 0% used [0x0000000720b20000, 0x0000000720b20000, 0x0000000723790000)
concurrent mark-sweep generation total 2519040K, used 2123204K [0x0000000726400000, 0x00000007c0000000, 0x00000007c0000000)
Metaspace used 341907K, capacity 402760K, committed 687488K, reserved 1640448K
class space used 38870K, capacity 47018K, committed 95616K, reserved 1048576K
2016-05-31T12:47:08.303+0000: 550384.634: [GC (GCLocker Initiated GC) 2016-05-31T12:47:08.303+0000: 550384.634: [ParNew: 732120K->2438K(773696K), 0.0228934 secs] 2855324K->2125771K(3292736K), 0.0231999 secs] [Times: user=0.07 sys=0.00, real=0.03 secs]
Heap after GC invocations=331321 (full 1587):
par new generation total 773696K, used 2438K [0x00000006f4400000, 0x0000000726400000, 0x0000000726400000)
eden space 728192K, 0% used [0x00000006f4400000, 0x00000006f4400000, 0x0000000720b20000)
from space 45504K, 5% used [0x0000000720b20000, 0x0000000720d81bc8, 0x0000000723790000)
to space 45504K, 0% used [0x0000000723790000, 0x0000000723790000, 0x0000000726400000)
concurrent mark-sweep generation total 2519040K, used 2123332K [0x0000000726400000, 0x00000007c0000000, 0x00000007c0000000)
Metaspace used 341907K, capacity 402760K, committed 687488K, reserved 1640448K
class space used 38870K, capacity 47018K, committed 95616K, reserved 1048576K
}
2016-05-31T12:47:08.334+0000: 550384.665: [GC (CMS Initial Mark) [1 CMS-initial-mark: 2123332K(2519040K)] 2135637K(3292736K), 0.0151574 secs] [Times: user=0.03 sys=0.00, real=0.01 secs]
2016-05-31T12:47:08.349+0000: 550384.681: [CMS-concurrent-mark-start]
{Heap before GC invocations=331321 (full 1588):
par new generation total 773696K, used 730630K [0x00000006f4400000, 0x0000000726400000, 0x0000000726400000)
eden space 728192K, 100% used [0x00000006f4400000, 0x0000000720b20000, 0x0000000720b20000)
from space 45504K, 5% used [0x0000000720b20000, 0x0000000720d81bc8, 0x0000000723790000)
to space 45504K, 0% used [0x0000000723790000, 0x0000000723790000, 0x0000000726400000)
concurrent mark-sweep generation total 2519040K, used 2123332K [0x0000000726400000, 0x00000007c0000000, 0x00000007c0000000)
Metaspace used 341907K, capacity 402760K, committed 687488K, reserved 1640448K
class space used 38870K, capacity 47018K, committed 95616K, reserved 1048576K
2016-05-31T12:47:09.419+0000: 550385.751: [GC (Allocation Failure) 2016-05-31T12:47:09.419+0000: 550385.751: [ParNew: 730630K->11995K(773696K), 0.0311341 secs] 2853963K->2135459K(3292736K), 0.0314510 secs] [Times: user=0.10 sys=0.00, real=0.03 secs]
Heap after GC invocations=331322 (full 1588):
par new generation total 773696K, used 11995K [0x00000006f4400000, 0x0000000726400000, 0x0000000726400000)
eden space 728192K, 0% used [0x00000006f4400000, 0x00000006f4400000, 0x0000000720b20000)
from space 45504K, 26% used [0x0000000723790000, 0x0000000724346f10, 0x0000000726400000)
to space 45504K, 0% used [0x0000000720b20000, 0x0000000720b20000, 0x0000000723790000)
concurrent mark-sweep generation total 2519040K, used 2123463K [0x0000000726400000, 0x00000007c0000000, 0x00000007c0000000)
Metaspace used 341907K, capacity 402760K, committed 687488K, reserved 1640448K
class space used 38870K, capacity 47018K, committed 95616K, reserved 1048576K
}
推荐答案
该应用程序似乎在调试器下运行。线程转储指示该线程已挂在JDWP代理中。
Looks like the application is running under debugger. Thread Dump indicates that the thread is hung inside JDWP agent.
尝试禁用调试器。或者，您可以通过添加以下代理选项来打开JDWP日志记录：
Try to disable debugger. Alternatively you may turn on JDWP logging by adding the following agent options:
logfile=/path/to/jdwp.log,logflags=255
这篇关于为什么java newInstance挂在getDeclaredConstructors0上？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！