Viewing Data Distribution on GemFire Members

The following code can be used to show which member is hosting which primary piece of data in a partitioned region within GemFire. This was done with gemFire 7 but should work with GemFire 6.6 as well.

1. The server side cache.xml is as follows which pre populates some data into the region to save having to write a client to add data.

  
<?xml version="1.0"?>
<!DOCTYPE cache PUBLIC
    "-//GemStone Systems, Inc.//GemFire Declarative Caching 7.0//EN"
    "http://www.gemstone.com/dtd/cache7_0.dtd">

<cache>
    <cache-server port="40001" notify-by-subscription="true"/>
    <region name="exampleRegion">
      <region-attributes refid="PARTITION_REDUNDANT"/>
      <entry><key><string>1</string></key><value><string>MyValue1</string></value></entry>
      <entry><key><string>2</string></key><value><string>MyValue2</string></value></entry>
      <entry><key><string>3</string></key><value><string>MyValue3</string></value></entry>
      <entry><key><string>4</string></key><value><string>MyValue4</string></value></entry>
      <entry><key><string>5</string></key><value><string>MyValue5</string></value></entry>
      <entry><key><string>6</string></key><value><string>MyValue6</string></value></entry>
      <entry><key><string>7</string></key><value><string>MyValue7</string></value></entry>
      <entry><key><string>8</string></key><value><string>MyValue8</string></value></entry>
      <entry><key><string>9</string></key><value><string>MyValue9</string></value></entry>
      <entry><key><string>10</string></key><value><string>MyValue10</string></value></entry>
      <entry><key><string>11</string></key><value><string>MyValue11</string></value></entry>
      <entry><key><string>12</string></key><value><string>MyValue12</string></value></entry>
      <entry><key><string>13</string></key><value><string>MyValue13</string></value></entry>
      <entry><key><string>14</string></key><value><string>MyValue14</string></value></entry>
      <entry><key><string>15</string></key><value><string>MyValue15</string></value></entry>
      <entry><key><string>16</string></key><value><string>MyValue16</string></value></entry>
      <entry><key><string>17</string></key><value><string>MyValue17</string></value></entry>
      <entry><key><string>18</string></key><value><string>MyValue18</string></value></entry>
      <entry><key><string>19</string></key><value><string>MyValue19</string></value></entry>
      <entry><key><string>20</string></key><value><string>MyValue20</string></value></entry>
      <entry><key><string>21</string></key><value><string>MyValue21</string></value></entry>
      <entry><key><string>22</string></key><value><string>MyValue22</string></value></entry>
      <entry><key><string>23</string></key><value><string>MyValue23</string></value></entry>
      <entry><key><string>24</string></key><value><string>MyValue24</string></value></entry>
      <entry><key><string>25</string></key><value><string>MyValue25</string></value></entry>
      <entry><key><string>26</string></key><value><string>MyValue26</string></value></entry>
      <entry><key><string>27</string></key><value><string>MyValue27</string></value></entry>
      <entry><key><string>28</string></key><value><string>MyValue28</string></value></entry>
      <entry><key><string>29</string></key><value><string>MyValue29</string></value></entry>
      <entry><key><string>30</string></key><value><string>MyValue30</string></value></entry>
   </region>
</cache> 

2. When listing members we have one locator and 2 cache servers.

  
gfsh>list members;
  Name   | Id
-------- | -------------------------------------------------------
server2  | Pas-Apicellas-MacBook-Pro(server2:78035)<v2>:4641
server1  | Pas-Apicellas-MacBook-Pro(server1:78002)<v1>:13379
locator1 | Pas-Apicellas-MacBook-Pro(locator1:77992:locator):23631

3. Get a query to ensure we indeed have 30 entries in the region.

  
gfsh>query --query="select count(*) from /exampleRegion";

Result     : true
startCount : 0
endCount   : 20
Rows       : 1

Result
------
30

NEXT_STEP_NAME : END

4. Create an XML cache.xml file which will enable us to connect as a cache server to the Distributed System with storage disabled.

  
<?xml version="1.0"?>
<!DOCTYPE cache PUBLIC
    "-//GemStone Systems, Inc.//GemFire Declarative Caching 7.0//EN"
    "http://www.gemstone.com/dtd/cache7_0.dtd">

<cache>
  <cache-server port="0" />

  <region name="exampleRegion" >
       <region-attributes data-policy="partition" >
           <partition-attributes local-max-memory="0" redundant-copies="1"/>
           <subscription-attributes interest-policy="all"/>            
       </region-attributes>
  </region>
</cache> 

5. Write a java client with code as follows

  
package vmware.au.gemfire.demos.deptemp;

import java.util.Map;
import java.util.Set;

import com.gemstone.gemfire.cache.Cache;
import com.gemstone.gemfire.cache.CacheFactory;
import com.gemstone.gemfire.cache.Region;
import com.gemstone.gemfire.cache.partition.PartitionRegionHelper;
import com.gemstone.gemfire.distributed.DistributedMember;

public class VerifyDataLocations 
{
 private Cache cache = null;
   
 public VerifyDataLocations() 
 {
     CacheFactory cf = new CacheFactory();
     cf.set("cache-xml-file", "xml/datalocations-cache-no-storage.xml");
     cf.set("locators", "localhost[10334]");
     cache = cf.create();
 }

 public void run() throws InterruptedException
 {
  Region<String,String> exampleRegion = cache.getRegion("exampleRegion");
  System.out.println("exampleRegion size = " + exampleRegion.size());

     Set<Map.Entry<String, String>> entries = exampleRegion.entrySet();

     for (Map.Entry entry: entries) 
     {

       DistributedMember member = 
         PartitionRegionHelper.getPrimaryMemberForKey(exampleRegion, (String) entry.getKey());
       System.out.println
         (String.format("\"Primary Member [Host=%s, Id=%s - Key=%s, Value=%s]", 
          member.getHost(), member.getId(), entry.getKey(), (String) entry.getValue())); 
        
     }
     
     System.out.println("Sleeping for 20 seconds..");
     
        cache.close();
     
 }
 
 /**
  * @param args
  * @throws InterruptedException 
  */
 public static void main(String[] args) throws InterruptedException 
 {
  // TODO Auto-generated method stub
  VerifyDataLocations test = new VerifyDataLocations();
  test.run();
 }

}

6. Output as follows.

exampleRegion size = 30
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server2:78035):4641 - Key=20, Value=MyValue20]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server2:78035):4641 - Key=21, Value=MyValue21]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server2:78035):4641 - Key=22, Value=MyValue22]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server2:78035):4641 - Key=23, Value=MyValue23]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server2:78035):4641 - Key=24, Value=MyValue24]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server2:78035):4641 - Key=25, Value=MyValue25]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server2:78035):4641 - Key=26, Value=MyValue26]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server2:78035):4641 - Key=27, Value=MyValue27]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server2:78035):4641 - Key=28, Value=MyValue28]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server2:78035):4641 - Key=29, Value=MyValue29]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server2:78035):4641 - Key=30, Value=MyValue30]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server2:78035):4641 - Key=1, Value=MyValue1]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server2:78035):4641 - Key=2, Value=MyValue2]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server2:78035):4641 - Key=3, Value=MyValue3]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server2:78035):4641 - Key=4, Value=MyValue4]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server1:78002):13379 - Key=5, Value=MyValue5]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server1:78002):13379 - Key=6, Value=MyValue6]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server1:78002):13379 - Key=7, Value=MyValue7]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server1:78002):13379 - Key=8, Value=MyValue8]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server1:78002):13379 - Key=9, Value=MyValue9]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server1:78002):13379 - Key=10, Value=MyValue10]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server1:78002):13379 - Key=11, Value=MyValue11]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server1:78002):13379 - Key=12, Value=MyValue12]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server1:78002):13379 - Key=13, Value=MyValue13]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server1:78002):13379 - Key=14, Value=MyValue14]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server1:78002):13379 - Key=15, Value=MyValue15]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server1:78002):13379 - Key=16, Value=MyValue16]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server1:78002):13379 - Key=17, Value=MyValue17]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server1:78002):13379 - Key=18, Value=MyValue18]
"Primary Member [Host=Pas-Apicellas-MacBook-Pro.local, Id=Pas-Apicellas-MacBook-Pro(server1:78002):13379 - Key=19, Value=MyValue19]