memory leak in weblogic rmi driver - weblogic

Question

We are having a memory leak issue after we started to use our existing Weblogic Datasource from our standalone apps. Standalone apps and WL Datasource does not lay in the same server. We are retrieving datasource with JNDI via t3 protocol.
We have used the approach down here.
https://docs.oracle.com/cd/E13222_01/wls/docs51/classdocs/API_jndi.html
87% of heap is allocated with weblogic/jdbc/rmi/internal/StructImpl_oracle_sql_STRUCT objects. This objects are in package RMI(Remote Method Invocation) and the problem itself started to appear after this remote usage. Since these two things happened at the same time we are suspicious that if we have done something wrong in the process of remote Datasource usage.
Everything works fine but we are restarting the nodes every 2-3 days and started to became a burden to us.
What can be the causes of this memory leak? Should we change anything in datasource properties or do we need to pass extra JVM parameters?
Here is a snapshot of our heap
Here is the weblogic properties.
Weblogic major version 10.3.6.0
Patch level: 10.3.6.0.181016 (October 2018 PSU - GENM)
Java version: Java HotSpot(TM) 64-Bit Server VM (build 20.45-b01, mixed mode) - 1.6.0_45
MEM_ARGS="-Xms4096m -Xmx6144m -Xmn1024m -XX:SurvivorRatio=8 -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:PermSize=256m -XX:MaxPermSi
ze=512m -verbosegc -XX:+PrintGCTimeStamps -XX:+PrintGCDetails -Xloggc:${LOGDIR}/GC_logs.${SERVER_NAME} -XX:+UseGCLogFileRotation -XX
:+PrintGCDateStamps -XX:NumberOfGCLogFiles=100 -XX:GCLogFileSize=512M"
--- EXTRA JAVA OPTIONS
-DASA_MARK=ASA_VERSION_2016.02.17"
-Dweblogic.management.server=${ADMIN_URL}"
-DHostName_WLSName=${value_hostname}-${WLS_NAME}"
-Dweblogic.system.BootIdentityFile=${DOMAIN_HOME}/boot.properties"
-Dweblogic.rjvm.enableprotocolswitch=true"
-Djava.net.preferIPv4Stack=true"
Here is our standalone app properties
[wlsadmin#machine1 cfg]$ /usr/java/jdk1.6.0_26/bin/java -version
java version "1.6.0_26"
Java(TM) SE Runtime Environment (build 1.6.0_26-b03)
Java HotSpot(TM) 64-Bit Server VM (build 20.1-b02, mixed mode)
CLASSPATH=$CLASSPATH:$HOME/lib/wlfullclient.jar
[wlsadmin#machine1 META-INF]$ more MANIFEST.MF
Manifest-Version: 1.0
Implementation-Vendor: Oracle Corp.
Implementation-Title: JDK 1.6 Client jar for WebLogic Server 10.3 Tue
Nov 15 08:52:36 PST 2011 1441050
Implementation-Version: 10.3.6.0
CLASSPATH=$CLASSPATH:$HOME/lib/ojdbc5.jar
[wlsadmin#machine1 META-INF]$ more MANIFEST.MF
Manifest-Version: 1.0
Specification-Title: "Oracle Globalization Development Kit"
Class-Path: orai18n-mapping.jar orai18n-utility.jar orai18n-collation.
jar orai18n-translation.jar orai18n-net.jar orai18n-servlet.jar orai1
8n-lcsd.jar orai18n-tools.jar gdk_custom.jar
Created-By: 1.5.0_07 (Sun Microsystems Inc.)
Main-Class: oracle.i18n.util.GDKOracleMetaData
Implementation-Title: "orai18n.jar archives"
Specification-Vendor: "Oracle Corporation"
Specification-Version: "Oracle Globalization Development Kit - 11.2.0.
1.0 - Production, Build : 11"
Implementation-Version: "Oracle Globalization Development Kit -
-Xms64m -Xmx256m

Answer 1

I am not able to guess what changes you can make in the relevant code, but based on the memory leak description - this is related to use of non thread safe hashmap.
It may help to try using ConcurrentHashMap.
Please check these links for more details:
https://support.oracle.com/knowledge/Middleware/1966075_1.html
https://javaeesupportpatterns.blogspot.com/2011/11/hashmap-thread-safe-problem-case-study.html