On Thursday 08 August 2013 02:29 AM, Attila Szegedi wrote:
- CompileUnit: While making fields non-final and nulling out fields is
certainly a solution, I don't like it as it feels fragile - you end up with an
object that has a member nulled out, and what if something later would want to
depend on it etc. As an example, consider CompileUnit, which now has its
ClassEmitter nulled out. Seems like architecturally it's a better idea is to
remove the field from the CompileUnit altogether, and use a composite object
being a tuple of (CompileUnit, ClassEmitter) in the compiler, and only pass
down the CompileUnit part of the tuple to things in the IR package that require
it.
While code can be refactored for a longer term, as of now, it does leak
memory. Moment class is loaded, we don't need lots of info maintained by
ASM's ClassEmitter. I suggest we go with short term solution and revisit
refactoring changes to FunctionNode/CompileUnit/Compiler later.
- Another issue I have is with synchronization in the Global object; I'd rather use a
ConcurrentMap and the (new for Java 8) computeIfAbsent() method.
<http://download.java.net/jdk8/docs/api/java/util/Map.html#computeIfAbsent(K,
java.util.function.Function)>. If you don't want to rely on computeIfAbsent() (but
I don't see why wouldn't you, frankly), you could still use a composition of get()
and putIfAbsent().
We still don't use any jdk8 specific API in nashorn codebase yet (I
believe). I'll restructure this with older API.
- In NativeArray, you could factor out the pattern of getting an invoker for an
iterator callback repeated across 4 methods into a method taking a key and a
return type.
Will do.
- Ostensibly, NativeObject could just use Global.TO_STRING instead of having
its own now. Not too convinced about this, as these things sort-of represent
call sites, so maybe it's okay as it is.
Yes - it is a different callsite (although I doubt how much InvokeByName
and dynamic invokers help now!)
- We still keep GlobalObject interface around?
Yes - we do. That calls for more refactorings. As I said, I'd like to
keep it minimal (as much as possible) for now.
- Why does RecompilableScriptFunctionData.ensureHasAllocator have to be synchronized? If we
absolutely need atomic updates to the allocator field, I'd consider using an AtomicReference for it
instead. Having synchronization in path of every "new SomeClass()" bothers me. Even if
it's completely unsynced and the field is not volatile, we only "risk" creating the
method handle multiple times; shouldn't be a big deal as we're (a) rarely multithreaded and (b)
it's idempotent. So, I'd rather choose a bit of a statistical redundancy than a certain performance
hit.
- Why does ensureCodeGenerated have to be synchronized? Can the modifications
of fields possibly occur on multiple threads? I mean,
functionNode.canSpecialize() will be determined at first execution and fields
nulled out. Also, wouldn't a second call to ensureCodeGenerated() after
functionNode was nulled out (if that's possible) result in a NPE on
functionNode.isLazy(), or is this guarded by !code.isEmpty()? At least this
synchronization only happens once on every linking event and not on every
invocation, unlike allocate() but I still don't really see the necessity.
I'll check again.
-Sundar
Attila.
On Aug 7, 2013, at 6:56 PM, A. Sundararajan
<[email protected]> wrote:
Please review http://cr.openjdk.java.net/~sundar/8022524/
Thanks
-Sundar
