Hmm, that makes sense. Is there an internal object reference I can use that does stay stable?
And sorry if this wasn't clear from my message, but as I know nothing yet of v8 do you have any pointers to the source where assignment occurs? On Thursday, October 4, 2018 at 2:28:42 PM UTC+2, Yang Guo wrote: > > Unfortunately this won't work 100% of the time. V8's GC may move objects, > so the address you would need to watch is not fixed. > > Yang > > On Thu, Oct 4, 2018 at 2:25 PM <eloy.d...@gmail.com <javascript:>> wrote: > >> Hi, >> >> I’m completely new to v8, so bare with me. Because the node debugging >> facility lacks the ability to define watchpoints (i.e. break when a >> variable changes), I was thinking that maybe I could do so at the VM level >> using lldb/gdb. >> >> The code I’m trying to debug tries to access a global variable, which >> somewhere during execution gets set to `null`. A pseudo example looks like: >> >> ``` >> var doc = document >> debugger // <- here the object is a non-null value as expected >> // Enzyme (a React testing utility) renders an async React tree and >> somewhere during that period `document` gets set to `null` >> mount(<SomeComponentThatDoesAsyncRendering />) // <- an exception is >> raised because `document` is `null` >> ``` >> >> My thinking is: >> >> 1. I use node/v8’s JS debugger to hit a breakpoint where I know the >> variable is what I expect it to be >> 2. break using lldb/gdb, find the JS variable >> 3. set a native watchpoint or a conditional breakpoint on the VM code >> that assigns variables for the address of the JS variable >> 4. when the native breakpoint hits, get a JS execution stack trace to >> find the location that is assigning the new (`null`) value >> >> Does this make any sense? >> >> Cheers, >> Eloy >> >> -- >> -- >> v8-dev mailing list >> v8-...@googlegroups.com <javascript:> >> http://groups.google.com/group/v8-dev >> --- >> You received this message because you are subscribed to the Google Groups >> "v8-dev" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to v8-dev+un...@googlegroups.com <javascript:>. >> For more options, visit https://groups.google.com/d/optout. >> > -- -- v8-dev mailing list v8-dev@googlegroups.com http://groups.google.com/group/v8-dev --- You received this message because you are subscribed to the Google Groups "v8-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to v8-dev+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
