If your transactional scripts contain function declarations that you instantiate, even if they are global, you'll inadvertantly cause polymorphism on the second run. That will slow down significantly. You can avoid this by only rerunning scripts that call/instantiate existing functions. Alternatively you can turn off the compilation cache; which will help with runtime (not load time though) if you reload all scripts.
(Btw, you might want to turn off handle zapping as well...) Hth, Toon On Tue, Mar 24, 2015, 09:29 Danny Dorfman <wilderness...@gmail.com> wrote: > Hello there, > > I have an issue with some code running JavaScript under V8, The code runs > in a *single* Isolate, that has *one* context. > The context is created, populated with some scripts, the scripts are > executed, and then the context is Exit()ed. The Isolate stays intact. > The above sequence repeats itself several times, with the *same* scripts > running time and again. This is what I call a series of "transactions". > > What happens, is after the initial transaction is executed, all the > subsequent ones experience a drastic slowdown (sometimes 7 times slower). > I tried profiling the code with* oprofile*, and I see this picture: > > *Fast transaction:* > PU: Intel Ivy Bridge microarchitecture, speed 3401 MHz (estimated) > Counted CPU_CLK_UNHALTED events (Clock cycles when not halted) with a unit > mask of 0x00 (No unit mask) count 100000 > samples % image name symbol name > 2444 1.8590 libv8.so > v8::internal::HandleScope::ZapRange(v8::internal::Object**, > v8::internal::Object**) > 1849 1.4064 libv8.so v8::internal::HeapObject::map() > const > 1537 1.1691 libv8.so v8::base::NoBarrier_Load(long > const volatile*) > 1417 1.0778 libv8.so > v8::internal::SmiTagging<8ul>::SmiToInt(v8::internal::Object const*) > 1286 0.9782 libv8.so > v8::internal::FixedArrayBase::length() const > 1273 0.9683 libpthread-2.13.so pthread_getspecific > 1250 0.9508 libv8.so > v8::internal::MapWord::MapWord(unsigned long) > 1235 0.9394 libv8.so > v8::internal::FixedArray::get(int) const > 1171 0.8907 libv8.so v8::base::Acquire_Load(long > const volatile*) > 1029 0.7827 libv8.so void > v8::base::CallOnce<void>(long*, v8::base::OneArgFunction<void*>::type, > void*) > 1021 0.7766 libv8.so > v8::internal::HeapObject::map_word() const > ..... > > *Slow transaction:* > CPU: Intel Ivy Bridge microarchitecture, speed 3401 MHz (estimated) > Counted CPU_CLK_UNHALTED events (Clock cycles when not halted) with a unit > mask of 0x00 (No unit mask) count 100000 > samples % image name symbol name > 27474 8.4737 libv8.so v8::internal::HeapObject::map() > const > 17271 5.3268 libv8.so > v8::internal::MapWord::MapWord(unsigned long) > 15862 4.8923 libv8.so > v8::internal::Map::instance_type() > 14754 4.5505 libv8.so v8::base::NoBarrier_Load(long > const volatile*) > 13941 4.2998 libv8.so > v8::internal::HeapObject::map_word() const > 13573 4.1863 libv8.so > v8::internal::MapWord::FromRawValue(unsigned long) > 11299 3.4849 libv8.so > v8::internal::Internals::HasHeapObjectTag(v8::internal::Object const*) > 10365 3.1968 libv8.so > v8::internal::Object::IsInternalizedString() const > 8469 2.6121 libv8.so > v8::internal::HeapObject::cast(v8::internal::Object const*) > 8085 2.4936 libv8.so > v8::internal::Object::IsHeapObject() const > 6350 1.9585 libv8.so > v8::internal::Object::IsOddball() const > 6105 1.8829 libv8.so > v8::internal::Embedded::Embedded() > 5777 1.7818 libv8.so > v8::internal::MapWord::ToRawValue() > 5670 1.7488 libv8.so v8::internal::MapWord::ToMap() > ... > > Any idea what is happening here? Why is the same code running so slowly > the second (third, etc) time around? > > Regards, > Danny > > -- > -- > v8-users mailing list > v8-users@googlegroups.com > http://groups.google.com/group/v8-users > --- > You received this message because you are subscribed to the Google Groups > "v8-users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to v8-users+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- -- v8-users mailing list v8-users@googlegroups.com http://groups.google.com/group/v8-users --- You received this message because you are subscribed to the Google Groups "v8-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to v8-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
