3256896 - Memory issue for Mail Sender Adapter related to java.lang.String.toLowerCase

There is a new error affecting PI/PO systems, with the following observations:

• PO system is running version 7.5, at Support Package 22 or above.
• The issue occurs while using mail channel.
• There is a noticeable overall system slowness, impacting areas such as monitoring, channels, and adapters.
• The system is experiencing OutOfMemory (OOM) dumps with errors similar to the ones bellow in .hprof file: 

The thread com.sap.engine.core.thread.execution.CentralExecutor$SingleThread keeps local variables occupying a significant portion of memory.

The memory is retained by a single instance of CentralExecutor$SingleThread, loaded by a ResourceMultiParentClassLoader, contributing significantly to heap usage.

The stacktrace of this thread shows accumulation in standard Java methods:

java.util.Arrays.copyOfRange
java.lang.String.<init>
java.lang.String.toLowerCase
com.sap.aii.af.sdk.xi.net.MIMEInputSource.decodeParts

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Thread Dumps are showing memory issues as well, in bold the important entries:

HTTP Worker thread at java.lang.OutOfMemoryError.<init>() (OutOfMemoryError.java)
at java.util.Arrays.copyOfRange (Arrays.java)
at java.lang.String.<init> (String.java)
at java.lang.String.toLowerCase (String.java)
at com.sap.aii.af.sdk.xi.net.MIMEInputSource.decodeParts (MIMEInputSource.java)
at com.sap.aii.af.sdk.xi.net.MIMEInputSource.readBody (MIMEInputSource.java)
at com.sap.aii.af.sdk.xi.net.MIMEInputSource.parse (MIMEInputSource.java)
at com.sap.aii.adapter.xi.ms.XIMessage.createMessageContext (XIMessage.java)
at com.sap.aii.adapter.xi.ms.XIMessage.<init> (XIMessage.java)

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• SAP NetWeaver
• SAP Process Integration

PO OOM error, PO slowness issue, SAP mail channel memory leak, CentralExecutor thread dump, MIMEInputSource decodeParts error, SAP PO 7.5 SP22+, OutOfMemoryError PO, PO mail channel issue, PO performance degradation, XIMessage memory usage, SAP PO thread memory, MIMEInputSource Java OOM, SAP PO OutOfMemory troubleshooting, SAP PO hprof analysis, SAP PO system monitoring slowness. , KBA , BC-XI-CON-MAI , Mail Adapter , Problem