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https://issues.apache.org/jira/browse/AXIS-2597?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Rodrigo Ruiz updated AXIS-2597:
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Attachment: SimpleUUIDGen.diff
Elwin, it seems you are wrong. From the code snippet you show in the
description, the variable is already declared static, and initialized in a
static block. This means it is only created once per class-loader.
I think the UUID standard comprises several algorithms for building the
identifiers. This would explain why there are more than one generator.
Most of the generation time in SimpleUUIDGen is spent on random value
generation. This is because it uses a SecureRandom instance, which is rather
slow.
I believe this class must not be changed too much, as the algorithm must be
kept standard compliant.
If you do not require secure random generation, you may better use the default
one (FastUUIDGen, in the same package).
I have tried to improve the execution time by moving some of the code to the
static block, and optimizing some of the private methods. The times changed
from 16000ms to 12000ms for 100 ids. This means an improvement of around 25%. I
attach the patch for these changes.
> CLONE -SimpleUUIDGen.nextUUID() is very, very, very slow
> --------------------------------------------------------
>
> Key: AXIS-2597
> URL: https://issues.apache.org/jira/browse/AXIS-2597
> Project: Axis
> Issue Type: Bug
> Affects Versions: 1.1
> Environment: Any
> Reporter: Elwin Ho
> Attachments: SimpleUUIDGen.diff
>
>
> It takes .4917 seconds to generate just one UUID. (Yes, seconds.) This
> renders the feature very nearly useless.
> In SimpleUUIDGen, there is a simple, but very expensive, bug.. It creates a
> new instance of SecureRandom on each call to nextUUID(). Making a new
> instance of SecureRandom is very expensive because it has to set up the
> environment for producing cryptographically strong random numbers.
> The instance of SecureRandom should be in a static variable and init'ed just
> once. Then, you call getNextLong() when you want another number from it. It
> would be much faster that way without compromising the integrity of the UUIDs
> generated.
> BTW, If you look at the comment I copied from the code, it appears that this
> is what the developer meant to make the SecureRandom instance static, but
> forgot.
> /**
> * Creates a new UUID. The algorithm used is described by The Open Group.
> * See <a href="http://www.opengroup.org/onlinepubs/009629399/apdxa.htm";>
> * Universal Unique Identifier</a> for more details.
> * <p>
> * Due to a lack of functionality in Java, a part of the UUID is a secure
> * random. This results in a long processing time when this method is
> called
> * for the first time.
> */
> Here's a proposed fix. In the member variables, add the following.
> private static Random secureRandom = null;
> static {
> try {
> secureRandom = SecureRandom.getInstance("SHA1PRNG", "SUN");
> } catch (Exception e) {
> secureRandom = new Random();
> }
> }
> The, remove the code near line 235 where the SecureRandom is being created.
> This change should do it just once.
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