Logging VMware GemFire GatewaySender Queue Events

Barry Oglesby June 3, 2020

Introduction

VMware GemFire provides a mechanism to asynchronously distribute batches of events between two disparate DistributedSystems called a WAN topology. The events are stored in queues in the local DistributedSystem before being batched and distributed. For troubleshooting purposes, it is sometimes necessary to see the events in the queue, but there is no OOTB way to do this.

This is a how-to article that describes a way to log all the events in a GatewaySender queue.

GatewaySender Queue Implementation

There are two different kinds of GatewaySenders, namely serial and parallel. The queue for each is implemented differently.

Serial GatewaySender Queue

The serial GatewaySender queue is implemented by a collection of DistributedRegions, one per dispatcher thread.

A simplified architecture is shown below: Multiple SerialGatewaySenderEventProcessors connected to a ConcurrentSerialGatewaySenderEventProcessor inheriting from SerialGatewaySenderImpl

Parallel GatewaySender Queue

The parallel GatewaySender queue is implemented by a single PartitionedRegion colocated with the data Region attached to it. Each dispatcher thread processes a subset of the PartitionedRegion buckets.

A simplified architecture is shown below: Multiple ParallelGatewaySenderEventProcessors connected to a ConcurrentParallelGatewaySenderEventProcessor inheriting from ParallelGatewaySenderImpl

Queue Region Entries

The queue Region entries are keyed by continuously-increasing longs and valued by instances of GatewaySenderEventImpl, each of which defines several fields including:

region: the name of the Region on which the event occurs
operation: the operation (e.g. Create)
key: the modified key
value: the modified value
possible duplicate: whether the event may have been received in the remote DistributedSystem. It gets set to true after HA events (e.g. a server crashing).
event id: the originator of the event and other order-preserving information

Implementation

All source code described in this article as well as an example usage is available here.

For each input GatewaySender id, the LogGatewaySenderQueueFunction:

gets the GatewaySender
creates the appropriate GatewaySenderQueueLogger based on the type of GatewaySender
invokes logQueue on the GatewaySenderQueueLogger

The GatewaySenderQueueLogger:

gets the Region(s) implementing the GatewaySender queue
for serial GatewaySenders, gets and logs all entries sorted by key and grouped by dispatcher thread
for parallel GatewaySenders, gets and logs all primary and secondary entries either sorted by key or grouped by bucket

Serial GatewaySender

Get Queue Regions To get the serial GatewaySender’s Regions, stream its RegionQueues and for each get its Region like:

private List<Region> getRegions() {
 return ((InternalGatewaySender) this.sender).getQueues()
  .stream()
  .map(rq -> rq.getRegion())
  .sorted(Comparator.comparing(Region::getName))
  .collect(Collectors.toList());
}

Get Queue Region Contents To get the contents, stream the Regions and for each Region get its contents like:

private String getContents(List<Region> regions, String header) {
 return regions
  .stream()
  .map(br -> getRegion(br))
  .collect(Collectors.joining("\n\n", header, ""));
}
private String getRegion(Region region) {
 return getContents(region, getHeader(region));
}

Get Queue Entries Finally, to get each entry’s contents, stream the Region’s entries and for each entry, get its contents like below. One thing to note is that the getEntry method deserializes the data value. To avoid that, pass false as the argument to the getValueAsString method. That will show the value as a byte[].

protected String getContents(Map<Long,GatewayQueueEvent> region, String header) {
 return region.entrySet()
  .stream()
  .sorted(Map.Entry.comparingByKey())
  .map(entry -> getEntry(entry))
  .collect(Collectors.joining("\n", header, ""));
}
protected String getEntry(Map.Entry<Long,GatewayQueueEvent> entry) {
 GatewaySenderEventImpl gsei = (GatewaySenderEventImpl) entry.getValue();
 return new StringBuilder()
  .append("\t\tqueueKey=").append(entry.getKey())
  .append("; region=").append(gsei.getRegionPath())
  .append("; operation=").append(gsei.getOperation())
  .append("; eventKey=").append(gsei.getKey())
  .append("; value=").append(gsei.getValueAsString(true))
  .append("; possibleDuplicate=").append(gsei.getPossibleDuplicate())
  .append("; eventId=").append(gsei.getEventId().expensiveToString())
  .toString();
}

Example Output The primary server’s log file will contain a message like:

[info 2020/06/01 12:49:11.567 HST <ServerConnection on port 57136 Thread 4> tid=0x87] 
The queue for serial GatewaySender nyserial contains the following 1000 primary entries grouped by dispatcher:
Queue for dispatcher nyserial.0 contains the following 200 entries:
    queueKey=0; region=/Trade; operation=CREATE; eventKey=2; value=PDX[26084582,example.client.domain.Trade]{id=2}; possibleDuplicate=true; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x1030000|1;sequenceID=2]
    queueKey=1; region=/Trade; operation=CREATE; eventKey=7; value=PDX[26084582,example.client.domain.Trade]{id=7}; possibleDuplicate=false; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x1030000|1;sequenceID=7]
    ...
  Queue for dispatcher nyserial.1 contains the following 200 entries:
    queueKey=0; region=/Trade; operation=CREATE; eventKey=3; value=PDX[26084582,example.client.domain.Trade]{id=3}; possibleDuplicate=true; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x1030001|1;sequenceID=3]
    queueKey=1; region=/Trade; operation=CREATE; eventKey=8; value=PDX[26084582,example.client.domain.Trade]{id=8}; possibleDuplicate=false; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x1030001|1;sequenceID=8]
    ...
  Queue for dispatcher nyserial.2 contains the following 200 entries:
    queueKey=0; region=/Trade; operation=CREATE; eventKey=4; value=PDX[26084582,example.client.domain.Trade]{id=4}; possibleDuplicate=true; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x1030002|1;sequenceID=4]
    queueKey=1; region=/Trade; operation=CREATE; eventKey=9; value=PDX[26084582,example.client.domain.Trade]{id=9}; possibleDuplicate=false; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x1030002|1;sequenceID=9]
    ...
  Queue for dispatcher nyserial.3 contains the following 200 entries:
    queueKey=0; region=/Trade; operation=CREATE; eventKey=0; value=PDX[26084582,example.client.domain.Trade]{id=0}; possibleDuplicate=true; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x1030003|1;sequenceID=0]
    queueKey=1; region=/Trade; operation=CREATE; eventKey=5; value=PDX[26084582,example.client.domain.Trade]{id=5}; possibleDuplicate=true; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x1030003|1;sequenceID=5]
    ...
  Queue for dispatcher nyserial.4 contains the following 200 entries:
    queueKey=0; region=/Trade; operation=CREATE; eventKey=1; value=PDX[26084582,example.client.domain.Trade]{id=1}; possibleDuplicate=true; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x1030004|1;sequenceID=1]
    queueKey=1; region=/Trade; operation=CREATE; eventKey=6; value=PDX[26084582,example.client.domain.Trade]{id=6}; possibleDuplicate=true; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x1030004|1;sequenceID=6]
    ...

Any secondary server’s log file will contain a message like:

[info 2020/06/01 12:49:11.600 HST <ServerConnection on port 57163 Thread 4> tid=0x89] 
The queue for serial GatewaySender nyserial contains the following 1000 secondary entries grouped by dispatcher:
Queue for dispatcher nyserial.0 contains the following 200 entries:
    queueKey=0; region=/Trade; operation=CREATE; eventKey=2; value=PDX[26084582,example.client.domain.Trade]{id=2}; possibleDuplicate=false; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x1030000|1;sequenceID=2]
    queueKey=1; region=/Trade; operation=CREATE; eventKey=7; value=PDX[26084582,example.client.domain.Trade]{id=7}; possibleDuplicate=false; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x1030000|1;sequenceID=7]
    ...
  Queue for dispatcher nyserial.1 contains the following 200 entries:
    queueKey=0; region=/Trade; operation=CREATE; eventKey=3; value=PDX[26084582,example.client.domain.Trade]{id=3}; possibleDuplicate=false; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x1030001|1;sequenceID=3]
    queueKey=1; region=/Trade; operation=CREATE; eventKey=8; value=PDX[26084582,example.client.domain.Trade]{id=8}; possibleDuplicate=false; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x1030001|1;sequenceID=8]
    ...
  Queue for dispatcher nyserial.2 contains the following 200 entries:
    queueKey=0; region=/Trade; operation=CREATE; eventKey=4; value=PDX[26084582,example.client.domain.Trade]{id=4}; possibleDuplicate=false; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x1030002|1;sequenceID=4]
    queueKey=1; region=/Trade; operation=CREATE; eventKey=9; value=PDX[26084582,example.client.domain.Trade]{id=9}; possibleDuplicate=false; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x1030002|1;sequenceID=9]
    ...
  Queue for dispatcher nyserial.3 contains the following 200 entries:
    queueKey=0; region=/Trade; operation=CREATE; eventKey=0; value=PDX[26084582,example.client.domain.Trade]{id=0}; possibleDuplicate=false; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x1030003|1;sequenceID=0]
    queueKey=1; region=/Trade; operation=CREATE; eventKey=5; value=PDX[26084582,example.client.domain.Trade]{id=5}; possibleDuplicate=false; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x1030003|1;sequenceID=5]
    ...
  Queue for dispatcher nyserial.4 contains the following 200 entries:
    queueKey=0; region=/Trade; operation=CREATE; eventKey=1; value=PDX[26084582,example.client.domain.Trade]{id=1}; possibleDuplicate=false; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x1030004|1;sequenceID=1]
    queueKey=1; region=/Trade; operation=CREATE; eventKey=6; value=PDX[26084582,example.client.domain.Trade]{id=6}; possibleDuplicate=false; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x1030004|1;sequenceID=6]
    ...

Parallel GatewaySender

Get Queue Region The parallel GatewaySender Region is retrieved directly from the Cache like:

PartitionedRegion region = (PartitionedRegion) this.cache.getRegion(sender.getId() + ParallelGatewaySenderQueue.QSTRING);

Get Primary and Secondary LocalDataSets To get the primary LocalDataSet, use the code like:

Map<Long,GatewayQueueEvent> primaryData = PartitionRegionHelper.getLocalPrimaryData(region);

There isn’t an existing way to get the secondary LocalDataSet. To get it, use a method like:

private Map<Long,GatewayQueueEvent> getLocalSecondaryData(PartitionedRegion region) {
 Set<Integer> primaryBucketIds = region.getDataStore().getAllLocalPrimaryBucketIds();
 Set<Integer> allBucketIds = new HashSet<>(region.getDataStore().getAllLocalBucketIds());
 allBucketIds.removeAll(primaryBucketIds);
 return new LocalDataSet(region, allBucketIds);
}

Get Queue Entries Once the LocalDataSet has been retrieved, its entries can be gotten using the methods in the serial GatewaysSender case here.

Example Output Each server’s log file will contain messages for its primary and secondary queues like:

[info 2020/06/01 12:46:46.802 HST <ServerConnection on port 57163 Thread 2> tid=0x87] 
The queue for parallel GatewaySender ny contains the following 342 primary entries:
  queueKey=113; region=/Trade; operation=CREATE; eventKey=54; value=PDX[26084582,example.client.domain.Trade]{id=54}; possibleDuplicate=false; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x10000|1;sequenceID=54;bucketID=0]
  queueKey=117; region=/Trade; operation=CREATE; eventKey=58; value=PDX[26084582,example.client.domain.Trade]{id=58}; possibleDuplicate=false; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x10004|1;sequenceID=58;bucketID=4]
  ...
[info 2020/06/01 12:46:46.884 HST <ServerConnection on port 57163 Thread 2> tid=0x87] 
The queue for parallel GatewaySender ny contains the following 331 secondary entries:
  queueKey=116; region=/Trade; operation=CREATE; eventKey=57; value=PDX[26084582,example.client.domain.Trade]{id=57}; possibleDuplicate=false; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x10003|1;sequenceID=57;bucketID=3]
  queueKey=118; region=/Trade; operation=CREATE; eventKey=59; value=PDX[26084582,example.client.domain.Trade]{id=59}; possibleDuplicate=false; eventId=EventID[xxx.xxx.x.xx(client:loner):57269:e48f0f72:client;threadID=0x10005|1;sequenceID=59;bucketID=5]
  ...

Get Primary and Secondary BucketRegions To get the local primary BucketRegions, use code like:

Set<BucketRegion> primaryBucketRegions = region.getDataStore().getAllLocalPrimaryBucketRegions();

There isn’t an existing way to get the secondary BucketRegions. To get them, use a method like:

private Set<BucketRegion> getAllLocalSecondaryBucketRegions(PartitionedRegion region) {
 Set<BucketRegion> primaryBucketRegions = region.getDataStore().getAllLocalPrimaryBucketRegions();
 Set<BucketRegion> allBucketRegions = new HashSet<>(region.getDataStore().getAllLocalBucketRegions());
 allBucketRegions.removeAll(primaryBucketRegions);
 return allBucketRegions;
}

Get Queue Entries by Bucket To get the contents, stream the BucketRegions and for each BucketRegion get its contents like:

private String getContents(Set<BucketRegion> bucketRegions, String header) {
 return bucketRegions
  .stream()
  .sorted(Comparator.comparingInt(BucketRegion::getId))
  .map(br -> getBucketRegion(br))
  .collect(Collectors.joining("\n\n", header, ""));
}
private String getBucketRegion(BucketRegion bucketRegion) {
 return getContents(bucketRegion, getHeader(bucketRegion));
}

Each BucketRegion’s entries can be gotten using the methods in the serial GatewaysSender case here.