At most one thread can run concurrently, but the performance still will delay.
On Tuesday, December 16, 2014 11:18:36 AM UTC+8, Tom Fan wrote:
>
> I modified the test code, it will create and destory thread at loop,
> thread do very simple thing which construct v8::locker and destruct it. I
> found a few million cycles, the speed thread of execution slow down
> absolutely, and the memory consumption continues to increase slowly.
>
> #include <pthread.h>
>
> #include <v8.h>
>
> #include <sys/time.h>
>
>
>
> double GetTime()
>
> {
>
> timeval tv;
>
> gettimeofday(&tv, NULL);
>
> return tv.tv_sec + (double)tv.tv_usec * 0.000001;
>
> }
>
>
>
> v8::Isolate *isolate;
>
>
>
> class Thread
>
> {
>
> public:
>
> static void* Start(void *thread)
>
> {
>
> static_cast<Thread*>(thread)->Start_();
>
> }
>
> private:
>
> void Start_()
>
> {
>
> v8::Locker locker(isolate);
>
> }
>
> };
>
>
>
> void test(pthread_t tid[], Thread thread[])
>
> {
>
> for (int i = 0; i < 1; ++i)
>
> {
>
> pthread_create(&tid[i], NULL, Thread::Start, &thread[i]);
>
> }
>
> for (int i = 0; i < 1; ++i)
>
> {
>
> pthread_join(tid[i], NULL);
>
> }
>
> }
>
>
>
> int main(int argc, char* argv[])
>
> {
>
> v8::V8::Initialize();
>
> isolate = v8::Isolate::New();
>
> {
>
> pthread_t tid[1024];
>
> Thread thread[1024];
>
> for (long long i = 0; i < 1000 * 1000 * 1000 * 1000llu; ++i)
>
> {
>
> double s = GetTime();
>
> test(tid, thread);
>
> printf("%d. %f\n", i+1, GetTime() - s);
>
> }
>
> }
>
> isolate->Dispose();
>
> v8::V8::Dispose();
>
> }
>
>
>
>
>
> <https://lh6.googleusercontent.com/-k9kAjBeeh88/VI-i2rJ8HUI/AAAAAAAAAII/yCVL0N6tsms/s1600/b1.png>
>
> <https://lh3.googleusercontent.com/-cUaA-JgmfZw/VI-i8qpxvRI/AAAAAAAAAIY/CGTIkf9xZ0A/s1600/b2.png>
>
>
>
> <https://lh5.googleusercontent.com/-jYtPKqSoP-o/VI-kLqk3mNI/AAAAAAAAAI4/lG9O689fM2s/s1600/Screenshot%2Bfrom%2B2014-12-16%2B11%3A15%3A42.png>
>
>
> <https://lh4.googleusercontent.com/-BL-Z1QPCNNg/VI-kXfO76LI/AAAAAAAAAJI/QkeeR2kh-OA/s1600/a2.png>
>
>
>
>
>
>
>
>
>
>
>
>
> On Monday, December 15, 2014 8:36:25 PM UTC+8, Jakob Kummerow wrote:
>>
>> An isolate has a table with per-thread data, which is implemented as a
>> linked list and scanned linearly. So yes, when a single isolate has seen
>> many threads, locking it will become slower. Since there's typically no
>> reason to access the same isolate with thousands of threads, I wouldn't
>> consider this a bug.
>>
>> On Mon, Dec 15, 2014 at 11:42 AM, <[email protected]> wrote:
>>>
>>>
>>> <https://lh6.googleusercontent.com/-sPNEtxGhqEc/VI6531u4HQI/AAAAAAAAAHw/2rZtAitF4bM/s1600/Screenshot%2Bfrom%2B2014-12-15%2B18%3A10%3A09.png>
>>> My Os is fedora20, v8 version is v8-3.25.30,
>>> first loop consumes 0.02 second, and then the 172th's loop consumes
>>> 2.48second.
>>>
>>> #include <pthread.h>
>>> #include <v8.h>
>>> #include <sys/time.h>
>>>
>>> double GetTime()
>>> {
>>> timeval tv;
>>> gettimeofday(&tv, NULL);
>>> return tv.tv_sec + (double)tv.tv_usec * 0.000001;
>>> }
>>>
>>> v8::Isolate *isolate;
>>>
>>> class Thread
>>> {
>>> public:
>>> static void* Start(void *thread)
>>> {
>>> static_cast<Thread*>(thread)->Start_();
>>> }
>>> private:
>>> void Start_()
>>> {
>>> v8::Locker locker(isolate);
>>> v8::Isolate::Scope scope(isolate);
>>> }
>>>
>>> };
>>>
>>> void test(pthread_t tid[], Thread thread[])
>>> {
>>> for (int i = 0; i < 1024; ++i)
>>> {
>>> pthread_create(&tid[i], NULL, Thread::Start, &thread[i]);
>>> }
>>> for (int i = 0; i < 1024; ++i)
>>> {
>>> pthread_join(tid[i], NULL);
>>> }
>>> }
>>>
>>> int main(int argc, char* argv[])
>>> {
>>> v8::V8::Initialize();
>>> isolate = v8::Isolate::New();
>>> {
>>> pthread_t tid[1024];
>>> Thread thread[1024];
>>> for (int i = 0; i < 1000 * 1000 * 1000; ++i)
>>> {
>>> double s = GetTime();
>>> test(tid, thread);
>>> printf("%d. %f\n", i+1, GetTime() - s);
>>> }
>>> }
>>> isolate->Dispose();
>>> v8::V8::Dispose();
>>> }
>>>
>>> --
>>> --
>>> v8-dev mailing list
>>> [email protected]
>>> http://groups.google.com/group/v8-dev
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>>
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