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Possible memory leakage writing item on subscription
September 25, 2013
15:30, EEST
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d.zinato
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September 25, 2013
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Hi all, i have this problem : testing your OPC UA Client, i wrapped it into an OSGi bundle ( i’m working on Eclipse Equinox).
I created a simple thread that writes every second a random integer value on a MemoryBased variable (I’m using Kepware OPC UA Server).

If i register my variable on a MonitoredDataItemListener, the java process memory (Private Bytes) raises from 151 mb to 155 mb in less than an hour.
Instead, if i don’t use a MonitoredDataItemListener, and maintain the same write procedure, the process memory is more stable (~0.2 Mb in 30 minutes).

I’m not able to understand if this is a real leak, or it is a normal memory fluctuation, and with a long-time run it disappears….is it possible to run the evaluation library for an entire day (and not only for 2 hours)?

Otherwise, this is my write procedure :

public void writeItem(String itemFullName, Object value) throws Exception {
//translate itemFullName, i.e. MB.LW_MONITOR.LW_HEART_BEAT_TH1 , in a ReferenceDescription
ReferenceDescription found=util.getItemReference(itemFullName);
NodeId nodeId=client.getNamespaceTable().toNodeId(found.getNodeId());
UaNode node = client.getAddressSpace().getNode(nodeId);
if(node==null) throw new Exception(“Null node!”);
UaVariable v = (UaVariable) node;
if (v.getDataType() == null)
v.setDataType(client.getAddressSpace().getType(v.getDataTypeId()));
UaDataType dataType = (UaDataType) v.getDataType();
Object convertedValue=null;
try {
convertedValue = dataType != null ? client.getAddressSpace().getDataTypeConverter().parseVariant(value.toString(), dataType): value;
} catch (Exception e) {
logger.log(LogService.LOG_ERROR,”writeItem ERROR on writing [“+itemFullName+”] as [“+value+”] : ” + LogUtils.getMessageAndStackTrace(e));
}
boolean status = client.writeAttribute(nodeId, Attributes.Value,convertedValue);
if(!status)
logger.log(LogService.LOG_WARNING, “Item “+itemFullName+” written ASYNCROUSLY @ “+value);
}

I register the item using this procedure (my test item is member of an OPC Group, and i register all the variables of this group):

// get the reference to MB.LW_MONITOR group
ReferenceDescription found=util.getGroupReference(groupName);
List itemList = this.client.getAddressSpace().browse(client.getNamespaceTable().toNodeId(found.getNodeId()));
// create a subscription instance for entire group
Subscription subscription =new Subscription();
for(ReferenceDescription rd:itemList){
NodeId nd=client.getNamespaceTable().toNodeId(rd.getNodeId());
MonitoredDataItem mi=new MonitoredDataItem(nd, Attributes.Value, MonitoringMode.Reporting);
mi.addChangeListener(cacheListener); // cacheListener is my MonitoredDataItemListener instance…
subscription.addItem(mi);
}
// add subscription to the client
client.addSubscription(subscription);

thanks

September 25, 2013
18:34, EEST
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Jouni Aro
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I suggest you first use jvisualvm or jconsole, which are both available in the JDK bin folder, to monitor memory usage. It gives much better picture of the actual memory usage than the Windows Task Manager.

September 26, 2013
13:19, EEST
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d.zinato
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September 25, 2013
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Hi Jouni,

thank you for your response.
I yet tried JVisualVM, and i didn’t find the same behaviour.
The heap memory is always under control (but I saw a lot of thread, also 50-60, all named Blocking-Work-Executorxxx and this kind of thread lives for 10 seconds, and then dies….is it normal?)

I’d like run my test program for at least 1 day, or 1 week, to see the real memory behaviour…..is it possible? Can i have a license for at least 24-hour run?

thank you

September 26, 2013
14:26, EEST
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Jouni Aro
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Yes, the stack uses a thread pool for sending the service requests to the server, so the thread behavior is normal.

Please, send an email to our support and we will see what we can do for you.

September 27, 2013
15:50, EEST
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d.zinato
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September 25, 2013
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Can you give me the right email address?
I only have this : sales@prosysopc.com
thanks

September 27, 2013
20:12, EEST
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Jouni Aro
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uajava-support at prosysopc dot com

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