On Fri, 25 Apr 2025 03:16:09 GMT, Chen Liang <[email protected]> wrote:
>> In the Throwable::printStackTrace method, StringBuilder is created multiple
>> times to build String. By sharing StringBuilder to build String, object
>> allocation and copying are reduced.
>>
>> In the scenario without suppressed and ourCause, unused IdentityHashMap is
>> not created.
>>
>> Through these optimizations, the performance of `new
>> Exception().printStackTrace()` can be improved by about 10%.
>
> src/java.base/share/classes/java/lang/Throwable.java line 749:
>
>> 747: // Print suppressed exceptions, if any
>> 748: for (Throwable se : getSuppressed())
>> 749: se.printEnclosedStackTrace(s, trace, SUPPRESSED_CAPTION,
>
> Shouldn't SUPPRESSED_CAPTION be added a prefix?
>
> I think we should revert the `prefixCaption` argument change; you should add
> a line `String prefixCaption = prefix.concat(caption);` instead.
The reason for using prefixCaption is that javac can do constant folding when
it is placed at the call site of the printStackTrace method.
> src/java.base/share/classes/java/lang/Throwable.java line 785:
>
>> 783: StackTraceElement[] trace,
>> 784: int traceEnd,
>> 785: int framesInCommon) {
>
> You just need to pass `framesInCommon`, can calculate `int limit =
> trace.length - framesInCommon;` and then for the loop below, `for (int i = 0;
> i < limit; i++)` instead of using `traceEnd`
According to your suggestion, I removed the passing of framesInCommon, which
can be calculated by `trace.length - 1 - traceEnd`
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PR Review Comment: https://git.openjdk.org/jdk/pull/24864#discussion_r2059513887
PR Review Comment: https://git.openjdk.org/jdk/pull/24864#discussion_r2059515401
