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.
