分析Art虚拟机的trace原理,相关源码都位于/art/runtime目录:
/art/runtime/
- signal_catcher.cc
- runtime.cc
- intern_table.cc
- thread_list.cc
- java_vm_ext.cc
- class_linker.cc
- gc/heap.cc
一、概述
Android 6.0系统采用的art虚拟机,所有的Java进程都运行在art之上,当应用发生ANR(Application Not Response,其中最终的一个环节便是向目标进程发送信号SIGNAL_QUIT, 传统的linux则是终止程序并输出core;而对于Android进程来说当收到SIGQUIT时,Java层面的进程都是跑在虚拟机之上的,ART虚拟机会捕获该信号,并输出相应的traces信息保存到目录/data/anr/traces.txt。
当然也可以通过一条命令来获取指定进程的traces信息,例如输出pid=888的进程信息:
执行完该命令后traces信息的结果保存到文件/data/anr/traces.txt,如下:
//[见小节2.2]
----- pid 888 at 2016-11-11 22:22:22 -----
Cmd line: system_server
ABI: arm
Build type: optimized
//[见小节3.1]
Zygote loaded classes=4113 post zygote classes=3239
//[见小节3.2]
Intern table: 57550 strong; 9315 weak
//共加载16动态库 [见小节3.3]
JNI: CheckJNI is off; globals=2418 (plus 115 weak)
Libraries: /system/lib/libandroid.so /system/lib/libandroid_servers.so /system/lib/libaudioeffect_jni.so /system/lib/libcompiler_rt.so /system/lib/libjavacrypto.so /system/lib/libjnigraphics.so /system/lib/libmedia_jni.so /system/lib/librs_jni.so /system/lib/libsechook.so /system/lib/libshell_jni.so /system/lib/libsoundpool.so /system/lib/libwebviewchromium_loader.so /system/lib/libwifi-service.so /vendor/lib/libalarmservice_jni.so /vendor/lib/liblocationservice.so libjavacore.so (16)
//已分配堆内存大小40MB,其中29M已用,总分配207772个对象 [见小节3.4]
Heap: 27% free, 29MB/40MB; 307772 objects
... //省略GC相关信息
//当前进程总99个线程[见小节3.5]
DALVIK THREADS (99):
//主线程调用栈[见小节3.6]
"main" prio=5 tid=1 Native
| group="main" sCount=1 dsCount=0 obj=0x75bd9fb0 self=0x5573d4f770
| sysTid=12078 nice=-2 cgrp=default sched=0/0 handle=0x7fa75fafe8
| state=S schedstat=( 5907843636 827600677 5112 ) utm=453 stm=137 core=0 HZ=100
| stack=0x7fd64ef000-0x7fd64f1000 stackSize=8MB
| held mutexes=
//内核栈[见小节3.6.2]
kernel: __switch_to+0x70/0x7c
kernel: SyS_epoll_wait+0x2a0/0x324
kernel: SyS_epoll_pwait+0xa4/0x120
kernel: cpu_switch_to+0x48/0x4c
native:
native:
native:
native:
native:
native:
at android.os.MessageQueue.nativePollOnce(Native method)
at android.os.MessageQueue.next(MessageQueue.java:323)
at android.os.Looper.loop(Looper.java:135)
at com.android.server.SystemServer.run(SystemServer.java:290)
at com.android.server.SystemServer.main(SystemServer.java:175)
at java.lang.reflect.Method.invoke!(Native method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:738)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:628)
"Binder_1" prio=5 tid=8 Native
| group="main" sCount=1 dsCount=0 obj=0x12c610a0 self=0x5573e5c750
| sysTid=12092 nice=0 cgrp=default sched=0/0 handle=0x7fa2743450
| state=S schedstat=( 796240075 863170759 3586 ) utm=50 stm=29 core=1 HZ=100
| stack=0x7fa2647000-0x7fa2649000 stackSize=1013KB
| held mutexes=
kernel: __switch_to+0x70/0x7c
kernel: binder_thread_read+0xd78/0xeb0
kernel: binder_ioctl_write_read+0x178/0x24c
kernel: binder_ioctl+0x2b0/0x5e0
kernel: do_vfs_ioctl+0x4a4/0x578
kernel: SyS_ioctl+0x5c/0x88
kernel: cpu_switch_to+0x48/0x4c
native:
native:
native:
native:
native:
native:
native:
native:
native:
native:
native:
(no managed stack frames)
... //此处省略剩余的N个线程.
接下来从虚拟机角度说说目标进程收到该信号的处理过程,每一行关键信息都说明其所对应的输出方法。
二. ART信号捕获
2.1 SignalCatcher
[-> SignalCatcher.cc]
void* SignalCatcher::Run(void* arg) {
SignalCatcher* signal_catcher = reinterpret_cast<SignalCatcher*>(arg);
Runtime* runtime = Runtime::Current();
Thread* self = Thread::Current();
DCHECK_NE(self->GetState(), kRunnable);
{
MutexLock mu(self, signal_catcher->lock_);
signal_catcher->thread_ = self;
signal_catcher->cond_.Broadcast(self);
}
SignalSet signals;
signals.Add(SIGQUIT);
signals.Add(SIGUSR1);
while (true) {
int signal_number = signal_catcher->WaitForSignal(self, signals);
if (signal_catcher->ShouldHalt()) {
runtime->DetachCurrentThread();
return nullptr;
}
switch (signal_number) {
case SIGQUIT:
signal_catcher->HandleSigQuit();
break;
case SIGUSR1:
signal_catcher->HandleSigUsr1();
break;
default:
LOG(ERROR) << "Unexpected signal %d" << signal_number;
break;
}
}
}
2.2 SignalCatcher::HandleSigQuit
[-> signal_catcher.cc]
void SignalCatcher::HandleSigQuit() {
Runtime* runtime = Runtime::Current();
std::ostringstream os;
os << "\n" << "----- pid " << getpid() << " at " << GetIsoDate() << " -----\n";
DumpCmdLine(os);
std::string fingerprint = runtime->GetFingerprint();
os << "Build fingerprint: '" << (fingerprint.empty() ? "unknown" : fingerprint) << "'\n";
os << "ABI: '" << GetInstructionSetString(runtime->GetInstructionSet()) << "'\n";
os << "Build type: " << (kIsDebugBuild ? "debug" : "optimized") << "\n";
runtime->DumpForSigQuit(os);
os << "----- end " << getpid() << " -----\n";
Output(os.str());
}
2.3 Runtime::DumpForSigQuit
[-> runtime.cc]
void Runtime::DumpForSigQuit(std::ostream& os) {
GetClassLinker()->DumpForSigQuit(os);
GetInternTable()->DumpForSigQuit(os);
GetJavaVM()->DumpForSigQuit(os);
GetHeap()->DumpForSigQuit(os);
TrackedAllocators::Dump(os);
os << "\n";
thread_list_->DumpForSigQuit(os);
BaseMutex::DumpAll(os);
}
三. trace信息
3.1 ClassLinker
[-> class_linker.cc]
void ClassLinker::DumpForSigQuit(std::ostream& os) {
Thread* self = Thread::Current();
if (dex_cache_image_class_lookup_required_) {
ScopedObjectAccess soa(self);
MoveImageClassesToClassTable();
}
ReaderMutexLock mu(self, *Locks::classlinker_classes_lock_);
os << "Zygote loaded classes=" << pre_zygote_class_table_.Size() << " post zygote classes="
<< class_table_.Size() << "\n";
}
3.2 InternTable
[-> intern_table.cc]
3.3 JavaVMExt
[-> java_vm_ext.cc]
void JavaVMExt::DumpForSigQuit(std::ostream& os) {
os << "JNI: CheckJNI is " << (check_jni_ ? "on" : "off");
if (force_copy_) {
os << " (with forcecopy)";
}
Thread* self = Thread::Current();
{
ReaderMutexLock mu(self, globals_lock_);
os << "; globals=" << globals_.Capacity();
}
{
MutexLock mu(self, weak_globals_lock_);
if (weak_globals_.Capacity() > 0) {
os << " (plus " << weak_globals_.Capacity() << " weak)";
}
}
os << '\n';
{
MutexLock mu(self, *Locks::jni_libraries_lock_);
os << "Libraries: " << Dumpable<Libraries>(*libraries_) << " (" << libraries_->size() << ")\n";
}
}
3.4 Heap
[-> heap.cc]
void Heap::DumpForSigQuit(std::ostream& os) {
os << "Heap: " << GetPercentFree() << "% free, " << PrettySize(GetBytesAllocated()) << "/"
<< PrettySize(GetTotalMemory()) << "; " << GetObjectsAllocated() << " objects\n";
DumpGcPerformanceInfo(os);
}
DumpGcPerformanceInfo()这个方法的参数非常多,先省略, 后续再单独用一篇文章来讲解.
3.5 ThreadList
[-> thread_list.cc]
void ThreadList::DumpForSigQuit(std::ostream& os) {
{
ScopedObjectAccess soa(Thread::Current());
if (suspend_all_historam_.SampleSize() > 0) {
Histogram<uint64_t>::CumulativeData data;
suspend_all_historam_.CreateHistogram(&data);
suspend_all_historam_.PrintConfidenceIntervals(os, 0.99, data); // Dump time to suspend.
}
}
Dump(os); // [见小节3.5.1]
DumpUnattachedThreads(os); //[见小节3.5.2]
}
3.5.1 Dump
[-> thread_list.cc]
void ThreadList::Dump(std::ostream& os) {
{
MutexLock mu(Thread::Current(), *Locks::thread_list_lock_);
//输出当前进程的线程个数
os << "DALVIK THREADS (" << list_.size() << "):\n";
}
DumpCheckpoint checkpoint(&os);
//执行checkpoint检查
size_t threads_running_checkpoint = RunCheckpoint(&checkpoint);
if (threads_running_checkpoint != 0) {
checkpoint.WaitForThreadsToRunThroughCheckpoint(threads_running_checkpoint);
}
}
DALVIK THREADS (25)
代表的是当前虚拟机中的线程个数为25. 另外, 此处RunCheckpoint方法比较重要,涉及进程的suspend状态问题.
3.5.2 DumpUnattachedThreads
[-> thread_list.cc]
分析Art虚拟机的trace原理,相关源码都位于/art/runtime目录:
/art/runtime/
- signal_catcher.cc
- runtime.cc
- intern_table.cc
- thread_list.cc
- java_vm_ext.cc
- class_linker.cc
- gc/heap.cc
一、概述
Android 6.0系统采用的art虚拟机,所有的Java进程都运行在art之上,当应用发生ANR(Application Not Response,其中最终的一个环节便是向目标进程发送信号SIGNAL_QUIT, 传统的linux则是终止程序并输出core;而对于Android进程来说当收到SIGQUIT时,Java层面的进程都是跑在虚拟机之上的,ART虚拟机会捕获该信号,并输出相应的traces信息保存到目录/data/anr/traces.txt。
当然也可以通过一条命令来获取指定进程的traces信息,例如输出pid=888的进程信息:
执行完该命令后traces信息的结果保存到文件/data/anr/traces.txt,如下:
//[见小节2.2]
----- pid 888 at 2016-11-11 22:22:22 -----
Cmd line: system_server
ABI: arm
Build type: optimized
//[见小节3.1]
Zygote loaded classes=4113 post zygote classes=3239
//[见小节3.2]
Intern table: 57550 strong; 9315 weak
//共加载16动态库 [见小节3.3]
JNI: CheckJNI is off; globals=2418 (plus 115 weak)
Libraries: /system/lib/libandroid.so /system/lib/libandroid_servers.so /system/lib/libaudioeffect_jni.so /system/lib/libcompiler_rt.so /system/lib/libjavacrypto.so /system/lib/libjnigraphics.so /system/lib/libmedia_jni.so /system/lib/librs_jni.so /system/lib/libsechook.so /system/lib/libshell_jni.so /system/lib/libsoundpool.so /system/lib/libwebviewchromium_loader.so /system/lib/libwifi-service.so /vendor/lib/libalarmservice_jni.so /vendor/lib/liblocationservice.so libjavacore.so (16)
//已分配堆内存大小40MB,其中29M已用,总分配207772个对象 [见小节3.4]
Heap: 27% free, 29MB/40MB; 307772 objects
... //省略GC相关信息
//当前进程总99个线程[见小节3.5]
DALVIK THREADS (99):
//主线程调用栈[见小节3.6]
"main" prio=5 tid=1 Native
| group="main" sCount=1 dsCount=0 obj=0x75bd9fb0 self=0x5573d4f770
| sysTid=12078 nice=-2 cgrp=default sched=0/0 handle=0x7fa75fafe8
| state=S schedstat=( 5907843636 827600677 5112 ) utm=453 stm=137 core=0 HZ=100
| stack=0x7fd64ef000-0x7fd64f1000 stackSize=8MB
| held mutexes=
//内核栈[见小节3.6.2]
kernel: __switch_to+0x70/0x7c
kernel: SyS_epoll_wait+0x2a0/0x324
kernel: SyS_epoll_pwait+0xa4/0x120
kernel: cpu_switch_to+0x48/0x4c
native:
native:
native:
native:
native:
native:
at android.os.MessageQueue.nativePollOnce(Native method)
at android.os.MessageQueue.next(MessageQueue.java:323)
at android.os.Looper.loop(Looper.java:135)
at com.android.server.SystemServer.run(SystemServer.java:290)
at com.android.server.SystemServer.main(SystemServer.java:175)
at java.lang.reflect.Method.invoke!(Native method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:738)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:628)
"Binder_1" prio=5 tid=8 Native
| group="main" sCount=1 dsCount=0 obj=0x12c610a0 self=0x5573e5c750
| sysTid=12092 nice=0 cgrp=default sched=0/0 handle=0x7fa2743450
| state=S schedstat=( 796240075 863170759 3586 ) utm=50 stm=29 core=1 HZ=100
| stack=0x7fa2647000-0x7fa2649000 stackSize=1013KB
| held mutexes=
kernel: __switch_to+0x70/0x7c
kernel: binder_thread_read+0xd78/0xeb0
kernel: binder_ioctl_write_read+0x178/0x24c
kernel: binder_ioctl+0x2b0/0x5e0
kernel: do_vfs_ioctl+0x4a4/0x578
kernel: SyS_ioctl+0x5c/0x88
kernel: cpu_switch_to+0x48/0x4c
native:
native:
native:
native:
native:
native:
native:
native:
native:
native:
native:
(no managed stack frames)
... //此处省略剩余的N个线程.
接下来从虚拟机角度说说目标进程收到该信号的处理过程,每一行关键信息都说明其所对应的输出方法。
二. ART信号捕获
2.1 SignalCatcher
[-> SignalCatcher.cc]
void* SignalCatcher::Run(void* arg) {
SignalCatcher* signal_catcher = reinterpret_cast<SignalCatcher*>(arg);
Runtime* runtime = Runtime::Current();
Thread* self = Thread::Current();
DCHECK_NE(self->GetState(), kRunnable);
{
MutexLock mu(self, signal_catcher->lock_);
signal_catcher->thread_ = self;
signal_catcher->cond_.Broadcast(self);
}
SignalSet signals;
signals.Add(SIGQUIT);
signals.Add(SIGUSR1);
while (true) {
int signal_number = signal_catcher->WaitForSignal(self, signals);
if (signal_catcher->ShouldHalt()) {
runtime->DetachCurrentThread();
return nullptr;
}
switch (signal_number) {
case SIGQUIT:
signal_catcher->HandleSigQuit();
break;
case SIGUSR1:
signal_catcher->HandleSigUsr1();
break;
default:
LOG(ERROR) << "Unexpected signal %d" << signal_number;
break;
}
}
}
2.2 SignalCatcher::HandleSigQuit
[-> signal_catcher.cc]
void SignalCatcher::HandleSigQuit() {
Runtime* runtime = Runtime::Current();
std::ostringstream os;
os << "\n" << "----- pid " << getpid() << " at " << GetIsoDate() << " -----\n";
DumpCmdLine(os);
std::string fingerprint = runtime->GetFingerprint();
os << "Build fingerprint: '" << (fingerprint.empty() ? "unknown" : fingerprint) << "'\n";
os << "ABI: '" << GetInstructionSetString(runtime->GetInstructionSet()) << "'\n";
os << "Build type: " << (kIsDebugBuild ? "debug" : "optimized") << "\n";
runtime->DumpForSigQuit(os);
os << "----- end " << getpid() << " -----\n";
Output(os.str());
}
2.3 Runtime::DumpForSigQuit
[-> runtime.cc]
void Runtime::DumpForSigQuit(std::ostream& os) {
GetClassLinker()->DumpForSigQuit(os);
GetInternTable()->DumpForSigQuit(os);
GetJavaVM()->DumpForSigQuit(os);
GetHeap()->DumpForSigQuit(os);
TrackedAllocators::Dump(os);
os << "\n";
thread_list_->DumpForSigQuit(os);
BaseMutex::DumpAll(os);
}
三. trace信息
3.1 ClassLinker
[-> class_linker.cc]
void ClassLinker::DumpForSigQuit(std::ostream& os) {
Thread* self = Thread::Current();
if (dex_cache_image_class_lookup_required_) {
ScopedObjectAccess soa(self);
MoveImageClassesToClassTable();
}
ReaderMutexLock mu(self, *Locks::classlinker_classes_lock_);
os << "Zygote loaded classes=" << pre_zygote_class_table_.Size() << " post zygote classes="
<< class_table_.Size() << "\n";
}
3.2 InternTable
[-> intern_table.cc]
3.3 JavaVMExt
[-> java_vm_ext.cc]
void JavaVMExt::DumpForSigQuit(std::ostream& os) {
os << "JNI: CheckJNI is " << (check_jni_ ? "on" : "off");
if (force_copy_) {
os << " (with forcecopy)";
}
Thread* self = Thread::Current();
{
ReaderMutexLock mu(self, globals_lock_);
os << "; globals=" << globals_.Capacity();
}
{
MutexLock mu(self, weak_globals_lock_);
if (weak_globals_.Capacity() > 0) {
os << " (plus " << weak_globals_.Capacity() << " weak)";
}
}
os << '\n';
{
MutexLock mu(self, *Locks::jni_libraries_lock_);
os << "Libraries: " << Dumpable<Libraries>(*libraries_) << " (" << libraries_->size() << ")\n";
}
}
3.4 Heap
[-> heap.cc]
void Heap::DumpForSigQuit(std::ostream& os) {
os << "Heap: " << GetPercentFree() << "% free, " << PrettySize(GetBytesAllocated()) << "/"
<< PrettySize(GetTotalMemory()) << "; " << GetObjectsAllocated() << " objects\n";
DumpGcPerformanceInfo(os);
}
DumpGcPerformanceInfo()这个方法的参数非常多,先省略, 后续再单独用一篇文章来讲解.
3.5 ThreadList
[-> thread_list.cc]
void ThreadList::DumpForSigQuit(std::ostream& os) {
{
ScopedObjectAccess soa(Thread::Current());
if (suspend_all_historam_.SampleSize() > 0) {
Histogram<uint64_t>::CumulativeData data;
suspend_all_historam_.CreateHistogram(&data);
suspend_all_historam_.PrintConfidenceIntervals(os, 0.99, data); // Dump time to suspend.
}
}
Dump(os); // [见小节3.5.1]
DumpUnattachedThreads(os); //[见小节3.5.2]
}
3.5.1 Dump
[-> thread_list.cc]
void ThreadList::Dump(std::ostream& os) {
{
MutexLock mu(Thread::Current(), *Locks::thread_list_lock_);
//输出当前进程的线程个数
os << "DALVIK THREADS (" << list_.size() << "):\n";
}
DumpCheckpoint checkpoint(&os);
//执行checkpoint检查
size_t threads_running_checkpoint = RunCheckpoint(&checkpoint);
if (threads_running_checkpoint != 0) {
checkpoint.WaitForThreadsToRunThroughCheckpoint(threads_running_checkpoint);
}
}
DALVIK THREADS (25)
代表的是当前虚拟机中的线程个数为25. 另外, 此处RunCheckpoint方法比较重要,涉及进程的suspend状态问题.
3.5.2 DumpUnattachedThreads
[-> thread_list.cc]
分析Art虚拟机的trace原理,相关源码都位于/art/runtime目录:
/art/runtime/
- signal_catcher.cc
- runtime.cc
- intern_table.cc
- thread_list.cc
- java_vm_ext.cc
- class_linker.cc
- gc/heap.cc
一、概述
Android 6.0系统采用的art虚拟机,所有的Java进程都运行在art之上,当应用发生ANR(Application Not Response,其中最终的一个环节便是向目标进程发送信号SIGNAL_QUIT, 传统的linux则是终止程序并输出core;而对于Android进程来说当收到SIGQUIT时,Java层面的进程都是跑在虚拟机之上的,ART虚拟机会捕获该信号,并输出相应的traces信息保存到目录/data/anr/traces.txt。
当然也可以通过一条命令来获取指定进程的traces信息,例如输出pid=888的进程信息:
执行完该命令后traces信息的结果保存到文件/data/anr/traces.txt,如下:
//[见小节2.2]
----- pid 888 at 2016-11-11 22:22:22 -----
Cmd line: system_server
ABI: arm
Build type: optimized
//[见小节3.1]
Zygote loaded classes=4113 post zygote classes=3239
//[见小节3.2]
Intern table: 57550 strong; 9315 weak
//共加载16动态库 [见小节3.3]
JNI: CheckJNI is off; globals=2418 (plus 115 weak)
Libraries: /system/lib/libandroid.so /system/lib/libandroid_servers.so /system/lib/libaudioeffect_jni.so /system/lib/libcompiler_rt.so /system/lib/libjavacrypto.so /system/lib/libjnigraphics.so /system/lib/libmedia_jni.so /system/lib/librs_jni.so /system/lib/libsechook.so /system/lib/libshell_jni.so /system/lib/libsoundpool.so /system/lib/libwebviewchromium_loader.so /system/lib/libwifi-service.so /vendor/lib/libalarmservice_jni.so /vendor/lib/liblocationservice.so libjavacore.so (16)
//已分配堆内存大小40MB,其中29M已用,总分配207772个对象 [见小节3.4]
Heap: 27% free, 29MB/40MB; 307772 objects
... //省略GC相关信息
//当前进程总99个线程[见小节3.5]
DALVIK THREADS (99):
//主线程调用栈[见小节3.6]
"main" prio=5 tid=1 Native
| group="main" sCount=1 dsCount=0 obj=0x75bd9fb0 self=0x5573d4f770
| sysTid=12078 nice=-2 cgrp=default sched=0/0 handle=0x7fa75fafe8
| state=S schedstat=( 5907843636 827600677 5112 ) utm=453 stm=137 core=0 HZ=100
| stack=0x7fd64ef000-0x7fd64f1000 stackSize=8MB
| held mutexes=
//内核栈[见小节3.6.2]
kernel: __switch_to+0x70/0x7c
kernel: SyS_epoll_wait+0x2a0/0x324
kernel: SyS_epoll_pwait+0xa4/0x120
kernel: cpu_switch_to+0x48/0x4c
native:
native:
native:
native:
native:
native:
at android.os.MessageQueue.nativePollOnce(Native method)
at android.os.MessageQueue.next(MessageQueue.java:323)
at android.os.Looper.loop(Looper.java:135)
at com.android.server.SystemServer.run(SystemServer.java:290)
at com.android.server.SystemServer.main(SystemServer.java:175)
at java.lang.reflect.Method.invoke!(Native method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:738)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:628)
"Binder_1" prio=5 tid=8 Native
| group="main" sCount=1 dsCount=0 obj=0x12c610a0 self=0x5573e5c750
| sysTid=12092 nice=0 cgrp=default sched=0/0 handle=0x7fa2743450
| state=S schedstat=( 796240075 863170759 3586 ) utm=50 stm=29 core=1 HZ=100
| stack=0x7fa2647000-0x7fa2649000 stackSize=1013KB
| held mutexes=
kernel: __switch_to+0x70/0x7c
kernel: binder_thread_read+0xd78/0xeb0
kernel: binder_ioctl_write_read+0x178/0x24c
kernel: binder_ioctl+0x2b0/0x5e0
kernel: do_vfs_ioctl+0x4a4/0x578
kernel: SyS_ioctl+0x5c/0x88
kernel: cpu_switch_to+0x48/0x4c
native:
native:
native:
native:
native:
native:
native:
native:
native:
native:
native:
(no managed stack frames)
... //此处省略剩余的N个线程.
接下来从虚拟机角度说说目标进程收到该信号的处理过程,每一行关键信息都说明其所对应的输出方法。
二. ART信号捕获
2.1 SignalCatcher
[-> SignalCatcher.cc]
void* SignalCatcher::Run(void* arg) {
SignalCatcher* signal_catcher = reinterpret_cast<SignalCatcher*>(arg);
Runtime* runtime = Runtime::Current();
Thread* self = Thread::Current();
DCHECK_NE(self->GetState(), kRunnable);
{
MutexLock mu(self, signal_catcher->lock_);
signal_catcher->thread_ = self;
signal_catcher->cond_.Broadcast(self);
}
SignalSet signals;
signals.Add(SIGQUIT);
signals.Add(SIGUSR1);
while (true) {
int signal_number = signal_catcher->WaitForSignal(self, signals);
if (signal_catcher->ShouldHalt()) {
runtime->DetachCurrentThread();
return nullptr;
}
switch (signal_number) {
case SIGQUIT:
signal_catcher->HandleSigQuit();
break;
case SIGUSR1:
signal_catcher->HandleSigUsr1();
break;
default:
LOG(ERROR) << "Unexpected signal %d" << signal_number;
break;
}
}
}
2.2 SignalCatcher::HandleSigQuit
[-> signal_catcher.cc]
void SignalCatcher::HandleSigQuit() {
Runtime* runtime = Runtime::Current();
std::ostringstream os;
os << "\n" << "----- pid " << getpid() << " at " << GetIsoDate() << " -----\n";
DumpCmdLine(os);
std::string fingerprint = runtime->GetFingerprint();
os << "Build fingerprint: '" << (fingerprint.empty() ? "unknown" : fingerprint) << "'\n";
os << "ABI: '" << GetInstructionSetString(runtime->GetInstructionSet()) << "'\n";
os << "Build type: " << (kIsDebugBuild ? "debug" : "optimized") << "\n";
runtime->DumpForSigQuit(os);
os << "----- end " << getpid() << " -----\n";
Output(os.str());
}
2.3 Runtime::DumpForSigQuit
[-> runtime.cc]
void Runtime::DumpForSigQuit(std::ostream& os) {
GetClassLinker()->DumpForSigQuit(os);
GetInternTable()->DumpForSigQuit(os);
GetJavaVM()->DumpForSigQuit(os);
GetHeap()->DumpForSigQuit(os);
TrackedAllocators::Dump(os);
os << "\n";
thread_list_->DumpForSigQuit(os);
BaseMutex::DumpAll(os);
}
三. trace信息
3.1 ClassLinker
[-> class_linker.cc]
void ClassLinker::DumpForSigQuit(std::ostream& os) {
Thread* self = Thread::Current();
if (dex_cache_image_class_lookup_required_) {
ScopedObjectAccess soa(self);
MoveImageClassesToClassTable();
}
ReaderMutexLock mu(self, *Locks::classlinker_classes_lock_);
os << "Zygote loaded classes=" << pre_zygote_class_table_.Size() << " post zygote classes="
<< class_table_.Size() << "\n";
}
3.2 InternTable
[-> intern_table.cc]
3.3 JavaVMExt
[-> java_vm_ext.cc]
void JavaVMExt::DumpForSigQuit(std::ostream& os) {
os << "JNI: CheckJNI is " << (check_jni_ ? "on" : "off");
if (force_copy_) {
os << " (with forcecopy)";
}
Thread* self = Thread::Current();
{
ReaderMutexLock mu(self, globals_lock_);
os << "; globals=" << globals_.Capacity();
}
{
MutexLock mu(self, weak_globals_lock_);
if (weak_globals_.Capacity() > 0) {
os << " (plus " << weak_globals_.Capacity() << " weak)";
}
}
os << '\n';
{
MutexLock mu(self, *Locks::jni_libraries_lock_);
os << "Libraries: " << Dumpable<Libraries>(*libraries_) << " (" << libraries_->size() << ")\n";
}
}
3.4 Heap
[-> heap.cc]
void Heap::DumpForSigQuit(std::ostream& os) {
os << "Heap: " << GetPercentFree() << "% free, " << PrettySize(GetBytesAllocated()) << "/"
<< PrettySize(GetTotalMemory()) << "; " << GetObjectsAllocated() << " objects\n";
DumpGcPerformanceInfo(os);
}
DumpGcPerformanceInfo()这个方法的参数非常多,先省略, 后续再单独用一篇文章来讲解.
3.5 ThreadList
[-> thread_list.cc]
void ThreadList::DumpForSigQuit(std::ostream& os) {
{
ScopedObjectAccess soa(Thread::Current());
if (suspend_all_historam_.SampleSize() > 0) {
Histogram<uint64_t>::CumulativeData data;
suspend_all_historam_.CreateHistogram(&data);
suspend_all_historam_.PrintConfidenceIntervals(os, 0.99, data); // Dump time to suspend.
}
}
Dump(os); // [见小节3.5.1]
DumpUnattachedThreads(os); //[见小节3.5.2]
}
3.5.1 Dump
[-> thread_list.cc]
void ThreadList::Dump(std::ostream& os) {
{
MutexLock mu(Thread::Current(), *Locks::thread_list_lock_);
//输出当前进程的线程个数
os << "DALVIK THREADS (" << list_.size() << "):\n";
}
DumpCheckpoint checkpoint(&os);
//执行checkpoint检查
size_t threads_running_checkpoint = RunCheckpoint(&checkpoint);
if (threads_running_checkpoint != 0) {
checkpoint.WaitForThreadsToRunThroughCheckpoint(threads_running_checkpoint);
}
}
DALVIK THREADS (25)
代表的是当前虚拟机中的线程个数为25. 另外, 此处RunCheckpoint方法比较重要,涉及进程的suspend状态问题.
3.5.2 DumpUnattachedThreads
[-> thread_list.cc]