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http://issues.apache.org/jira/browse/AXIS-1771?page=comments#action_58098 ]
Peter Molettiere commented on AXIS-1771:
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Hmm... I've spent the morning looking at your revised test, Venkat, but it
doesn't seem to hold up.
First, let me say that yes, your test as written, for the one small message
size that you test, does produce the number you're claiming. But for larger
message sizes, I'm seeing deserialization memory usage ratios as high as 42 to
1.
However, when I pull your reporting and garbage collection changes back into my
test, and run over a range of message sizes, your ratio doesn't remain
constant, even for the same message size that you test.
In answer to your question about what ratio is good enough, I'll say this. If
you could in fact get the ratio down to 15 to 1 it would be an improvement over
the current situation, and would be much appreciated, but O(15n) performance is
not ideal.
Here's what I'm seeing, for a few cases. You can run my code (will attach in a
minute) to see all cases.
[java] Created tree with 5 levels and 3 children at each level
[java] Total memory usage: Created tree = 912 KBytes (934232)
[java] Increase in allocation since last check = 229 KBytes (234736)
[java] Total memory usage: Serialized tree = 4 MBytes (4958272)
[java] Increase in allocation since last check = 3 MBytes (4024040)
[java] Total memory usage: Deserialized tree. = 13 MBytes (13692168)
[java] Increase in allocation since last check = 8 MBytes (8733896)
The above test represents a ratio of 13 to serialize, and 35 to deserialize.
[java] Created tree with 5 levels and 4 children at each level
[java] Total memory usage: Created tree = 1 MBytes (1908112)
[java] Increase in allocation since last check = 920 KBytes (942464)
[java] Total memory usage: Serialized tree = 27 MBytes (28685800)
[java] Increase in allocation since last check = 25 MBytes (26777688)
[java] Total memory usage: Deserialized tree. = 66 MBytes (69915592)
[java] Increase in allocation since last check = 39 MBytes (41229792)
The above test represents a ratio of 27 to serialize, and 42 to deserialize.
[java] Created tree with 5 levels and 5 children at each level
[java] Total memory usage: Created tree = 5 MBytes (6065264)
[java] Increase in allocation since last check = 4 MBytes (4247184)
[java] Total memory usage: Serialized tree = 95 MBytes (100226664)
[java] Increase in allocation since last check = 89 MBytes (94161400)
[java] Total memory usage: Deserialized tree. = 246 MBytes (258236984)
[java] Increase in allocation since last check = 150 MBytes (158010320)
The above test represents a ratio of 22 to serialize, and 38 to deserialize.
> Excessive Memory Use During Serialization/Deserialization
> ---------------------------------------------------------
>
> Key: AXIS-1771
> URL: http://issues.apache.org/jira/browse/AXIS-1771
> Project: Axis
> Type: Bug
> Components: Basic Architecture
> Versions: 1.2RC2
> Environment: JDK 1.4.2, Mac OS X, Linux, Windows
> Reporter: Peter Molettiere
> Assignee: Venkat Reddy
> Attachments: MTC_venkat.java, MemoryTesterClient.java,
> SOAPmsg_multiref_false.xml, SOAPmsg_multiref_true.xml,
> SerializationContext.java.diff, memory-use-test.tgz, recursion.png
>
> Axis uses pathological amounts of memory during the
> serialization/deserialization process.
> We see about a 30 to 1 ratio of memory used during (de)serialization to
> in-memory representation of the objects being (de)serialized. So ser/deser in
> axis of a 2M graph of objects uses 288M of memory! Further, the memory used
> seems to scale linearly with the size of the object graph being serialized.
> The memory used does seem to be released once serialization is done, so this
> isn't a leak.
> Using the attached example code, (based on the code used to demonstrate
> AXIS-1423) you can see this behavior. The test automatically runs with a max
> heap size of 1024M, and runs out of memory serializing a 28M object graph.
> As provided, it generates the following output:
> Buildfile: build.xml
> build:
> [javac] Compiling 1 source file to /Users/pietro/Work/Axis Memory
> Test/build/classes
> run:
> [java] - Unable to find required classes (javax.activation.DataHandler
> and javax.mail.internet.MimeMultipart). Attachment support is disabled.
> [java] Created tree with 5 levels and 3 children at each level
> [java] Axis used 13 MBytes to serialize 230 KBytes, a ratio of 30.0
> [java] GC freed 13 MBytes
> [java] Created tree with 5 levels and 4 children at each level
> [java] Axis used 71 MBytes to serialize 1 MBytes, a ratio of 31.0
> [java] GC freed 71 MBytes
> [java] Created tree with 5 levels and 5 children at each level
> [java] Axis used 288 MBytes to serialize 2 MBytes, a ratio of 51.0
> [java] GC freed 287 MBytes
> [java] Created tree with 5 levels and 6 children at each level
> [java] Axis used 671 MBytes to serialize 11 MBytes, a ratio of 29.0
> [java] GC freed 675 MBytes
> [java] Created tree with 5 levels and 7 children at each level
> [java] Out of Memory serializing 28 MBytes tree.
> [java] Java Result: 1
> BUILD SUCCESSFUL
> Total time: 2 minutes 51 seconds
> Note that the ratios are halved from the reported values, since it includes
> both serialization and deserialization of the object graph. So axis uses
> 30.5M to serialize a 1M message, and another 30.5M to deserialize it,
> resulting in the reported 71M reported above. Also, notice that the ratio
> stays close to 30 to 1 regardless of object graph size. This is the linear
> scaling I mention above.
> Note also, that if you tweak the code to generate very small object graphs,
> you see extremely high ratios, but I would expect this due to simple one-time
> overhead to operate on very small amounts of data. That's why I start with
> the graph size that I do.
>
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