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From "Shapira, Yoav" <Yoav.Shap...@mpi.com>
Subject RE: [COLLECTIONS] FastHashMap performance
Date Tue, 03 Jun 2003 19:52:47 GMT

Howdy,
Assuming I agree that GC and JIT play a role in my benchmark (which I
don't without further convincing), how should I disable them?

I see -XX:-DisableExplicitGC is a VM option, but it only disables
explicit System.gc() calls, which I don't use anyways.  I couldn't find
an option to disable JIT.

The heap has ample space to hold the objects in my benchmark.  My
results don't change if I increase -Xmx or change -Xms to match -Xmx.

Yoav Shapira
Millennium ChemInformatics


>-----Original Message-----
>From: Juozas Baliuka [mailto:baliuka@centras.lt]
>Sent: Tuesday, June 03, 2003 3:37 PM
>To: Jakarta Commons Developers List
>Subject: Re: [COLLECTIONS] FastHashMap performance
>
>
>I have tried to implement performance tests for maps, but it is not
>trivial.
>Try to dissable GC and JIT for performance tests.
>
>----- Original Message -----
>From: "Shapira, Yoav" <Yoav.Shapira@mpi.com>
>To: "Jakarta Commons Developers List" <commons-dev@jakarta.apache.org>
>Sent: Tuesday, June 03, 2003 9:05 PM
>Subject: RE: [COLLECTIONS] FastHashMap performance
>
>
>
>Howdy,
>I've had tests with both a normal hashmap (just new HashMap() used) and
>a synchronized wrapper (Collections.synchronizedMap(new HashMap()).  I
>would expect the normal HashMap to be faster than both the FastHashMap
>and the synchronized HashMap.  Is my expectation wrong?
>
>However, here are the results:
>[MapTest: FastHashMap: false / Synchronized wrapper: false / Insert
>time: 1592 / Read time: 30]
>[MapTest: FastHashMap: true / Synchronized wrapper: false / Insert
time:
>1265 / Read time: 6]
>[MapTest: FastHashMap: false / Synchronized wrapper: true / Insert
time:
>983 / Read time: 7]
>[MapTest: FastHashMap: false / Synchronized wrapper: false / Insert
>time: 1158 / Read time: 2]
>[MapTest: FastHashMap: true / Synchronized wrapper: false / Insert
time:
>1194 / Read time: 2]
>[MapTest: FastHashMap: false / Synchronized wrapper: true / Insert
time:
>827 / Read time: 2]
>[MapTest: FastHashMap: false / Synchronized wrapper: false / Insert
>time: 990 / Read time: 2]
>[MapTest: FastHashMap: true / Synchronized wrapper: false / Insert
time:
>1006 / Read time: 2]
>[MapTest: FastHashMap: false / Synchronized wrapper: true / Insert
time:
>732 / Read time: 2]
>[MapTest: FastHashMap: false / Synchronized wrapper: false / Insert
>time: 949 / Read time: 3]
>[MapTest: FastHashMap: true / Synchronized wrapper: false / Insert
time:
>1003 / Read time: 2]
>[MapTest: FastHashMap: false / Synchronized wrapper: true / Insert
time:
>1579 / Read time: 2]
>[MapTest: FastHashMap: false / Synchronized wrapper: false / Insert
>time: 888 / Read time: 2]
>[MapTest: FastHashMap: true / Synchronized wrapper: false / Insert
time:
>1045 / Read time: 2]
>[MapTest: FastHashMap: false / Synchronized wrapper: true / Insert
time:
>793 / Read time: 2]
>[MapTest: FastHashMap: false / Synchronized wrapper: false / Insert
>time: 1151 / Read time: 2]
>[MapTest: FastHashMap: true / Synchronized wrapper: false / Insert
time:
>855 / Read time: 2]
>[MapTest: FastHashMap: false / Synchronized wrapper: true / Insert
time:
>905 / Read time: 3]
>[MapTest: FastHashMap: false / Synchronized wrapper: false / Insert
>time: 1217 / Read time: 1]
>[MapTest: FastHashMap: true / Synchronized wrapper: false / Insert
time:
>1269 / Read time: 2]
>[MapTest: FastHashMap: false / Synchronized wrapper: true / Insert
time:
>1107 / Read time: 2]
>[MapTest: FastHashMap: false / Synchronized wrapper: false / Insert
>time: 1062 / Read time: 2]
>[MapTest: FastHashMap: true / Synchronized wrapper: false / Insert
time:
>1252 / Read time: 2]
>[MapTest: FastHashMap: false / Synchronized wrapper: true / Insert
time:
>971 / Read time: 2]
>[MapTest: FastHashMap: false / Synchronized wrapper: false / Insert
>time: 1460 / Read time: 2]
>[MapTest: FastHashMap: true / Synchronized wrapper: false / Insert
time:
>1404 / Read time: 2]
>[MapTest: FastHashMap: false / Synchronized wrapper: true / Insert
time:
>1110 / Read time: 2]
>[MapTest: FastHashMap: false / Synchronized wrapper: false / Insert
>time: 1278 / Read time: 2]
>[MapTest: FastHashMap: true / Synchronized wrapper: false / Insert
time:
>1193 / Read time: 2]
>[MapTest: FastHashMap: false / Synchronized wrapper: true / Insert
time:
>1096 / Read time: 2]
>
>Yoav Shapira
>Millennium ChemInformatics
>
>
>>-----Original Message-----
>>From: ericpabst@discoverfinancial.com
>>[mailto:ericpabst@discoverfinancial.com]
>>Sent: Tuesday, June 03, 2003 2:58 PM
>>To: Jakarta Commons Developers List
>>Subject: RE: [COLLECTIONS] FastHashMap performance
>>
>>
>>In your test, are you synchronizing the HashMap?  FastHashMap
>implements
>>smart synchronization.  It should not be compared with an
>unsynchronized
>>version of HashMap.
>>
>>P.S.  In fact, it might be nice to allow doing this smart
>synchronization
>>on *any* Map.  i.e. alternative to Collections.synchronizeMap(Map).
>>
>>Eric Pabst
>>Discover Financial Services
>>2500 Lake Park Blvd., 3N
>>West Valley City, UT 84120
>>Ph: 801.902.4636
>>Fax: 801.902.4123
>>
>>
>>
>>|---------+--------------------------->
>>|         |           "Shapira, Yoav" |
>>|         |           <Yoav.Shapira@mp|
>>|         |           i.com>          |
>>|         |                           |
>>|         |           06/03/03 12:54  |
>>|         |           PM              |
>>|         |           Please respond  |
>>|         |           to "Jakarta     |
>>|         |           Commons         |
>>|         |           Developers List"|
>>|         |                           |
>>|---------+--------------------------->
>>
>>----------------------------------------------------------------------
-
>-
>>---------------------------------------|
>>  |
>>|
>>  |        To:      "Jakarta Commons Developers List" <commons-
>>dev@jakarta.apache.org>                            |
>>  |        cc:
>>|
>>  |        Subject: RE: [COLLECTIONS] FastHashMap performance
>>|
>>
>>----------------------------------------------------------------------
-
>-
>>---------------------------------------|
>>
>>
>>
>>
>>
>>Howdy,
>>I understand it's just a wrapper, and that the
>>reading cannot be any faster.  I'm curious why the
>>writing is so much faster, even in the default (not fast)
>>mode of FastHashMap.
>>
>>Yoav Shapira
>>Millennium ChemInformatics
>>
>>
>>>-----Original Message-----
>>>From: Juozas Baliuka [mailto:baliuka@centras.lt]
>>>Sent: Tuesday, June 03, 2003 2:36 PM
>>>To: Jakarta Commons Developers List
>>>Subject: Re: [COLLECTIONS] FastHashMap performance
>>>
>>>FastHashMap can not be faster than HasMap in single thread just
>because
>>it
>>>uses HasMap to implement mappings:
>>>
>>> public Object get(Object key) {
>>>        if (fast) {
>>>            return (map.get(key));
>>>        } else {
>>>            synchronized (map) {
>>>                return (map.get(key));
>>>            }
>>>        }
>>>    }
>>>
>>>
>>>/**
>>>     * Construct an empty map.
>>>     */
>>>    public FastHashMap() {
>>>        super();
>>>        this.map = new HashMap();
>>>    }
>>>
>>>----- Original Message -----
>>>From: "Shapira, Yoav" <Yoav.Shapira@mpi.com>
>>>To: "Jakarta Commons Developers List"
<commons-dev@jakarta.apache.org>
>>>Sent: Tuesday, June 03, 2003 8:00 PM
>>>Subject: RE: [COLLECTIONS] FastHashMap performance
>>>
>>>
>>>Howdy,
>>>Neither did I, but I just ran the attached benchmark and got
>surprising
>>>results.  I hope the attachement comes through OK: if not I'll
re-post
>>>inline.  This benchmark has just one thread writing, one thread
>>reading,
>>>which I expected to be the case where FastHashMap is not as efficient
>>as
>>>HashMap.
>>>
>>>The benchmark inserts 100000 records in the map, then reads 1000 of
>>>those at random.  I run this 10 times for each map implemention.  I'm
>>>ignoring the first run read times as there's overhead in initializing
>>>the Random generator.
>>>
>>>I'm running this test on JDK 1.4.1, no special java switches, just
>java
>>>MapTest on the command line, on Solaris 8.
>>>
>>>I'm very curious to hear comments, ideas.  I was expecting to have to
>>>write another test with multiple writing threads, but if FastHashMap
>is
>>>faster even for the simple case, why ever use the regular HashMap?
>>>
>>>The results are:
>>>[MapTest: Map class: java.util.HashMap / Insert time: 1616 / Read
>time:
>>>30]
>>>[MapTest: Map class: org.apache.commons.collections.FastHashMap /
>>Insert
>>>time: 1252 / Read time: 6]
>>>[MapTest: Map class: java.util.HashMap / Insert time: 958 / Read
time:
>>>2]
>>>[MapTest: Map class: org.apache.commons.collections.FastHashMap /
>>Insert
>>>time: 1203 / Read time: 2]
>>>[MapTest: Map class: java.util.HashMap / Insert time: 820 / Read
time:
>>>2]
>>>[MapTest: Map class: org.apache.commons.collections.FastHashMap /
>>Insert
>>>time: 988 / Read time: 2]
>>>[MapTest: Map class: java.util.HashMap / Insert time: 781 / Read
time:
>>>2]
>>>[MapTest: Map class: org.apache.commons.collections.FastHashMap /
>>Insert
>>>time: 1033 / Read time: 3]
>>>[MapTest: Map class: java.util.HashMap / Insert time: 720 / Read
time:
>>>2]
>>>[MapTest: Map class: org.apache.commons.collections.FastHashMap /
>>Insert
>>>time: 1067 / Read time: 2]
>>>[MapTest: Map class: java.util.HashMap / Insert time: 1454 / Read
>time:
>>>2]
>>>[MapTest: Map class: org.apache.commons.collections.FastHashMap /
>>Insert
>>>time: 1267 / Read time: 2]
>>>[MapTest: Map class: java.util.HashMap / Insert time: 1534 / Read
>time:
>>>2]
>>>[MapTest: Map class: org.apache.commons.collections.FastHashMap /
>>Insert
>>>time: 862 / Read time: 2]
>>>[MapTest: Map class: java.util.HashMap / Insert time: 1433 / Read
>time:
>>>2]
>>>[MapTest: Map class: org.apache.commons.collections.FastHashMap /
>>Insert
>>>time: 844 / Read time: 2]
>>>[MapTest: Map class: java.util.HashMap / Insert time: 1578 / Read
>time:
>>>2]
>>>[MapTest: Map class: org.apache.commons.collections.FastHashMap /
>>Insert
>>>time: 1488 / Read time: 2]
>>>[MapTest: Map class: java.util.HashMap / Insert time: 1450 / Read
>time:
>>>2]
>>>[MapTest: Map class: org.apache.commons.collections.FastHashMap /
>>Insert
>>>time: 859 / Read time: 2]
>>>
>>>Yoav Shapira
>>>Millennium ChemInformatics
>>>
>>>
>>>>-----Original Message-----
>>>>From: Juozas Baliuka [mailto:baliuka@centras.lt]
>>>>Sent: Tuesday, June 03, 2003 1:53 PM
>>>>To: Jakarta Commons Developers List
>>>>Subject: Re: [COLLECTIONS] FastHashMap performance
>>>>
>>>>I do not think it is faster than java.util.HashMap, it is just
pseudo
>>>>thread
>>>>safe wrapper.
>>>>
>>>>----- Original Message -----
>>>>From: "Shapira, Yoav" <Yoav.Shapira@mpi.com>
>>>>To: <commons-dev@jakarta.apache.org>
>>>>Sent: Tuesday, June 03, 2003 7:17 PM
>>>>Subject: [COLLECTIONS] FastHashMap performance
>>>>
>>>>
>>>>
>>>>Howdy,
>>>>Has anyone benchmarked the performance of the FastHashMap and how it
>>>>compares to the java.util.HashMap implementation?  If so, are the
>>>>benchmarks available online somewhere?
>>>>
>>>>I don't doubt its quality nor its performance, just curious...
>Thanks,
>>>>
>>>>Yoav Shapira
>>>>Millennium ChemInformatics
>>>>
>>>>
>>>>
>>>>
>>>>
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>>>
>>>
>>>
>>>
>>>This e-mail, including any attachments, is a confidential business
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>>>and/or privileged.  This e-mail is intended only for the
individual(s)
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disclosed
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>>>----
>>>
>>>
>>>>
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>>
>>
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>intended
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>
>
>
>This e-mail, including any attachments, is a confidential business
>communication, and may contain information that is confidential,
>proprietary
>and/or privileged.  This e-mail is intended only for the individual(s)
to
>whom it is addressed, and may not be saved, copied, printed, disclosed
or
>used by anyone else.  If you are not the(an) intended recipient, please
>immediately delete this e-mail from your computer system and notify the
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