Re: [PATCH] 4851444: Exposing sun.reflect.Reflection#getCallerClass as a public API in Java 8

[Jörn Huxhorn]

On 20. September 2013 at 11:35:24, Peter Levart (peter.levart at gmail.com) wrote:
On 09/20/2013 10:57 AM, Jochen Theodorou wrote: 
> Am 20.09.2013 09:28, schrieb Nick Williams: 
> [...] 
>> This is all well and good, but some of us just need a simple array. 
>> This seems like over-engineering. I just want an array of 
>> StackFrameInfos/StackTraceFrames. 
> 
> if you need the full stack, then misusing a Predicate and a dummy 
> Consumer to collect everything looks a lot like not intended use. The 
> intended inability of lambdas to write to local variables outside the 
> lambda is not helping here to avoid anonymous inner classes. So what 
> was a simple method call, will look really awful - I agree. 

List<StackFrameInfo> frames = new ArrayList<>(); 
Thread.walkStack(frames::add); 

No so awfull. 

Regards, Peter 
This is precisely what I mean. Yes, it has a nice syntax but it will perform worse than simply working on a StackTraceFrame[].

It's not that awful but it's the construction of an additional ArrayList instance and n additional method calls plus additional gc heat.

We are talking about code that will be executed for every single log statement, i.e. millions/billions of times. This *will* add up and it *will* make a significant difference. This isn't premature optimization either - it's just a very hot hotspot.



Joern