May 2008 - jboss-dev-forums - Jboss List Archives

[Design of Messaging on JBoss (Messaging/JBoss)] - Re: Optimisations: A couple of low hanging fruits going for

by david.lloyd＠jboss.com

UTF-8 is a little more complex than that. Chars 0-0x7F are represented by one byte, 0-0x7F. Beyond that characters are represented with 2 to 4 bytes. This means that for every character there are multiple comparisons and shifts performed, with some extra bits being set or cleared for certain characters. UTF-16 on the other hand, being the native encoding for Java, is written one char at a time without transcoding - no shifts, no comparisons, no bitmasks. It's just a straight write of chars. You can't possibly do better than that in terms of processing speed. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4150822#4150822 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=4150822

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[Design of Messaging on JBoss (Messaging/JBoss)] - Re: Optimisations: A couple of low hanging fruits going for

by timfox

"trustin" wrote : | | for (int i = 0; i < str.length(); i ++) { | buf.putChar(str.charAt(i)); | } Well... UTF-8 is just putting a sequence of bytes generated from bitwise operations on the chars? So should be fast right? Maybe the overhead is due to the creation of the encoder class etc, I don't really know I haven't profiled it yet... Maybe we should just write our own encoding that writes directly onto a SimpleString... View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4150819#4150819 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=4150819

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[Design of Messaging on JBoss (Messaging/JBoss)] - Re: Optimisations: A couple of low hanging fruits going for

by timfox

"trustin" wrote : | This might also be useful: | | http://jug.safehaus.org/ Looks interesting. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4150818#4150818 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=4150818

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[Design of Messaging on JBoss (Messaging/JBoss)] - Re: MaxIO, MinFiles and JournalFileSize

by clebert.suconic＠jboss.com

Yes... that's what I meant when I said to keep the first freeFile opened. The freeFile concept will be used for the pre allocations only, and we will aways have 2 files opened. (The current and next) View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4150813#4150813 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=4150813

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[Design of Messaging on JBoss (Messaging/JBoss)] - Re: Optimisations: A couple of low hanging fruits going for

by trustin

"timfox" wrote : "timfox" wrote : | | Instead I think we should use a variant 2 UUID. | | http://www.webdav.org/specs/draft-leach-uuids-guids-01.txt This might also be useful: http://jug.safehaus.org/ View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4150811#4150811 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=4150811

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[Design of Messaging on JBoss (Messaging/JBoss)] - Re: Optimisations: A couple of low hanging fruits going for

by trustin

"timfox" wrote : "trustin" wrote : I'd prefer David's suggestion to use UTF-16 although it's not so efficient for ASCII strings. | | I'm not really sure I understand why UTF-16 is going to be more performant than UTF-8. It's because it's as simple as writing a series of short integers? It should look like this for example: for (int i = 0; i < str.length(); i ++) { buf.putChar(str.charAt(i)); } View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4150810#4150810 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=4150810

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[Design of Messaging on JBoss (Messaging/JBoss)] - Re: Optimisations: A couple of low hanging fruits going for

by timfox

"timfox" wrote : | Instead I think we should use a variant 2 UUID. http://www.webdav.org/specs/draft-leach-uuids-guids-01.txt View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4150807#4150807 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=4150807

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[Design of Messaging on JBoss (Messaging/JBoss)] - Re: Optimisations: A couple of low hanging fruits going for

by timfox

"trustin" wrote : I'd prefer David's suggestion to use UTF-16 although it's not so efficient for ASCII strings. I'm not really sure I understand why UTF-16 is going to be more performant than UTF-8. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4150803#4150803 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=4150803

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[Design of Messaging on JBoss (Messaging/JBoss)] - Re: Optimisations: A couple of low hanging fruits going for

by timfox

"jmesnil" wrote : | It seems the bottleneck is the generation of the UUID. | | When using UUID.randomUUID(), the implementation uses a SecureRandom. | If I use Random instead and creates the UUID with new UUID(rand.nextLong(), nextLong(), the perf increases significantely. | I don't think we should be using random UUIDs at all, since they're... well random (so can clash). Instead I think we should use a variant 2 UUID. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4150802#4150802 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=4150802

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[Design of Messaging on JBoss (Messaging/JBoss)] - Re: Optimisations: A couple of low hanging fruits going for

by trustin

"timfox" wrote : 2) Text messages. Currently text message bodies are encoded using UTF-8 with the encoding methods on the MINA IoBuffer class. This is slow (as mentioned in another thread). One of my friends told me just writing a byte array generated by String.getBytes(enc) performs better. YMMV though. I'd prefer David's suggestion to use UTF-16 although it's not so efficient for ASCII strings. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4150795#4150795 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=4150795

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jboss-dev-forums May 2008