Can you provide the V8 version you are using? Having a debug event listener should no longer cause significant performance regression.
You can use an interrupt (v8::Isolate::RequestInterrupt) to interrupt V8 to install a DebugEventListener. Yang On Tuesday, November 18, 2014 7:49:03 PM UTC+1, Evan Torrie wrote: > > > > On Thursday, October 30, 2014 5:29:13 AM UTC-7, Ben Noordhuis wrote: >> >> >> You can interrupt a running script by calling v8::Debug::DebugBreak() >> from another thread. It's de facto async signal-safe if, perhaps, not >> de jure; that is, I don't know whether V8 guarantees that it's async >> signal-safe but the current implementation is. >> >> You can do more advanced things programmatically with >> v8::Debug::SetDebugEventListener() and v8::Debug::SetMessageHandler(). >> See test/cctest/test-debug.cc for more details. >> > > This is useful info. I have a follow-up question. > > It appears as though SetDebugEventListener(), unlike DebugBreak(), must > be called in a thread-safe manner (i.e. it must enter the appropriate > isolate that it wants to install the DebugEventListener on). I say this > because looking at the v8 internal code, it appears to be creating handles, > scopes etc when installing the DebugEventListener callback. > > In my case, I'd like to install a DebugEventListener only in response to a > signal sent to the running process -- the reason being that installing a > DebugEventListener from the very beginning of the code appears to result in > a fairly major decrease in v8 Javascript performance (a factor of 3x > slowdown in my test application). > > So, I have a main thread running with the v8 isolate, and a separate > monitor thread running which is waiting for the SIGHUP. After setting a > hupFired flag, I want to then install the DebugEventListener from the > separate monitor thread - while the main thread may still be running its > code. After installing the DebugEventListener, I then want to fire a > DebugBreak event (so I can capture the stack trace of where the main v8 > thread is running). > > So far, I've been fairly unsuccessful in doing so -- in fact, I'm > wondering if this is even possible if the main v8 Javascript code is in an > infinite loop (the use case for which I want to interrupt it). I can > certainly send a DebugBreak event, but unless I have a DebugEventListener > installed, then I won't be able to get a callback to my own code. Or am I > missing something? > > Thanks for any help. > > > >> >> V8 used to have an embedded debug agent that created a TCP listen >> socket for clients to connect to. That was removed recently, you have >> to implement your own now. >> > -- -- v8-users mailing list [email protected] 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 [email protected]. For more options, visit https://groups.google.com/d/optout.
