java.util.UUID.fromString performance (original) (raw)

Vitaly Davidovich vitalyd at gmail.com
Tue Feb 28 14:40:23 UTC 2012

Alan,

Sorry I should've stated that I looked at this in detail in java 6 but only glanced at the UUID impl in 7 just now on my phone. If String.split() has a fast path now then forget my suggestion #1 :). Using Long.parseLong should still be applicable though.

Thanks

Sent from my phone On Feb 28, 2012 9:37 AM, "Alan Bateman" <Alan.Bateman at oracle.com> wrote:

On 28/02/2012 14:26, Vitaly Davidovich wrote:

Hi all,

I noticed that this method could be made a bit more performant by: 1) creating a statically initialized Pattern for "-" and then calling split() on that. Currently the method calls name.split() which compiles the pattern on each invocation. 2) use Long.parseLong() instead of Long.decode() to extract the bits. With these changes, the method runs at least 20% faster (some runs were significantly faster) on an Intel Westmere server and should be a bit more GC friendly. Any thoughts? I can send the full code a bit later when I'm in front of my computer. Thanks Sent from my phone Just on name.split, are you sure this is compiling a pattern each time? There is a fast path in String.split since jdk7 for the common case so I would not expect the regex code to be used. -Alan.

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