Does compression work for Externalizable?

[Si Rakov]

Hi,

Thanks for your help on my earlier question.  I found the config, and turned compression on.

However, I am not seeing any change in the size of the map, either with or without compression.  Should I be seeing a change?  We use java.io.Externalizable for our serialization.  Does compression work with that?

Thanks for your help!

yours

Si Rakov

[M. Sancar Koyunlu]

Yes, the compression should work for java.io.Externalizable as well. 

See the following test:
Note that I am using the private API here. It is not to be used on production but just to show that it works. 

public static class Test implements Externalizable {

    private long a;
    private long b;
    private long c;
    private long d;

    @Override
    public void writeExternal(ObjectOutput out) throws IOException {
        out.writeLong(a);
        out.writeLong(b);
        out.writeLong(c);
        out.writeLong(d);
    }

    @Override
    public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
        a = in.readLong();
        b = in.readLong();
        c = in.readLong();
        d = in.readLong();
    }
}

public static void main(String[] args) throws InterruptedException {

    {

        SerializationConfig serializationConfig = new SerializationConfig();
        serializationConfig.setEnableCompression(true);
        SerializationService serializationService = new DefaultSerializationServiceBuilder().setConfig(serializationConfig).build();
        System.out.println("COMPRESSED SIZE  " + serializationService.toData(new Test()).totalSize());
    }

    {
        SerializationService serializationService = new DefaultSerializationServiceBuilder().build();
        System.out.println("DEFAULT SIZE " + serializationService.toData(new Test()).totalSize());
    }
}

Note that I am using a private API. This API should not be used on production. 

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Sancar Koyunlu

Software Engineer

san...@hazelcast.com

2 W 5th Ave, Ste 300 | San Mateo, CA 94402 | USA +1 (650) 521-5453 | hazelcast.com

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[Si Rakov]

Hi Sancar,

Thank you so much.  Can you explain the following?  

1. When I enable compression, then log into my application without compression, I see the Hazelcast Management Center (HMC) showing a specific size committed to the map.  When I turn on compression and do the same thing, I see the same size committed to the map.  Do you know why this might be?  
2. Is the HMC showing the actual size of the map in both cases, or the decompressed size?  
3. If it is the decompressed size, how do I view the compressed size in the HMC?

Thanks for your help!

best

Simon Rakov

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[Si Rakov]

Let me amend the last message, because it was confusing.  Here are the cases:

a. Bring up HMC with compression disabled

b. Log into webapp that uses Hazelcast

c. View size of map

d. Logout

e. Restart HMC with compression enabled

f. Repeat (b)

g. Repeat (c)

h.  The size of the map at c and g are the same.  Why is this?

Thanks

Simon

[M. Sancar Koyunlu]

I did try with management center 5.0 and hazelcast 5.0

What do you mean by size exactly ? See the following screen shots where I run the member with compression on and off.


 I can see that EntryMemory is changing between the two runs 

After I write this message I read your message again and realize that there is a problem with step "e"

The compression should be enabled on the member/client which will load the data. The configuration of the ManagementCenter is not relevant. 

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[Si Rakov]

Hi,

I could see that the members were configured for compression.  I have been told that compression does not work at all in version 4, which is what I have been using.  Is this true?

Thanks

Si

[M. Sancar Koyunlu]

It should work with 4.0 as well. 

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[M. Sancar Koyunlu]

Hi again, 

I have tried with 4.2 members and 4.2 management center to make sure. I see the exact same memory sizes and effect of the compression as I shared in the previous email. 

Where are you loading the data from ? Client / Member / SQL interface ?
Can you share your hazelcast config of your members or clients if you have any ? 
Also you may share the screenshots of the management center for us to double check ?