liangjian created PLC4X-339:
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Summary: modbus connection causes memory leak
Key: PLC4X-339
URL: https://issues.apache.org/jira/browse/PLC4X-339
Project: Apache PLC4X
Issue Type: Bug
Components: Driver-Modbus
Affects Versions: 0.9.0
Environment: Windows 10; jdk1.8 32bit
Reporter: liangjian
Note: The version is 0.9.1.
1. The document (here)[https://plc4x.apache.org/users/protocols/modbus.html]
seems wrong. It tells me the connection string format is:
"modbus-tcp:tcp://127.0.0.1:502", but my test code throws exception saying no
driver until I change it to "modbus://127.0.0.1".
2. My test code writes (or reads) some value via modbus tcp every 1 second,
using short tcp connection (open and close every time). The memory increases
every second until out-of-memory. In process monitor I find the thread count
increases 1 every time the connection opens, but never releases, althought I
consider the `try-block` shall closes it automatically. In fact, I see it calls
`connection.close` after the `try-block`.
Test code:
```java
while (true) {
String connectionString = "modbus://127.0.0.1";
try (PlcConnection plcConnection = new
PlcDriverManager().getConnection(connectionString)) {
PlcWriteRequest.Builder builder =
plcConnection.writeRequestBuilder();
builder.addItem("value-1", "holding-register:1:DINT", 30000);
builder.addItem("value-2", "holding-register:3:REAL", 3.14);
PlcWriteRequest writeRequest = builder.build();
PlcWriteResponse response = writeRequest.execute().get();
for (String fieldName : response.getFieldNames()) {
if(response.getResponseCode(fieldName) ==
PlcResponseCode.OK) {
System.out.println("Value[" + fieldName + "]: updated");
}
// Something went wrong, to output an error message instead.
else {
System.out.println("Error[" + fieldName + "]: " +
response.getResponseCode(fieldName).name());
}
}
System.out.println("done");
}
Thread.sleep(1000);
}
```
It shows the connection is not cleaned properly.
I see it's more efficient to do this using long tcp connection (reuse 1
connection or use a pool). But short tcp connection should also work.
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