This error appears in the SystemOut.log.

[2/13/18 22:04:28:499 CST] 000012fa Ffdc          I com.ibm.ffdc.impl.Ffdc setFailsafeProvider FFDC1000I: FFDC provider com.ibm.ws.ffdc.impl.FfdcProvider@947fe3ef aborted, Exception follows
[2/13/18 22:04:28:500 CST] 000012fa Ffdc          I com.ibm.ffdc.impl.Ffdc setFailsafeProvider FFDC1001I: FFDC provider aborted with exception {0}
                                 java.nio.channels.ClosedByInterruptException
	at java.nio.channels.spi.AbstractInterruptibleChannel.end(AbstractInterruptibleChannel.java:221)
	at sun.nio.ch.FileChannelImpl.size(FileChannelImpl.java:325)
	at sun.nio.ch.FileChannelImpl.truncate(FileChannelImpl.java:335)
	at com.ibm.ws.ffdc.impl.FfdcProvider.logSummary(FfdcProvider.java:274)
	at com.ibm.ws.ffdc.impl.FfdcProvider.logSummary(FfdcProvider.java:151)
	at com.ibm.ffdc.util.provider.FfdcSummaryProvider.getIncident(FfdcSummaryProvider.java:40)
	at com.ibm.ffdc.util.provider.Ffdc.<init>(Ffdc.java:66)
	at com.ibm.ffdc.util.provider.FfdcProvider.getFfdc(FfdcProvider.java:281)
	at com.ibm.ffdc.impl.Ffdc.getFfdc(Ffdc.java:192)
	at com.ibm.ws.ffdc.FFDCFilter.processException(FFDCFilter.java:90)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:95)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:56)
	at java.lang.reflect.Method.invoke(Method.java:620)
	at com.ibm.websphere.ras.WsJrasTraceLogger.exception(WsJrasTraceLogger.java:1414)
	at com.ibm.CORBA.ras.Trc.ffdc(Trc.java:856)
	at com.ibm.rmi.transport.ReaderThread.run(ReaderPoolImpl.java:137)

This Stack Overflow article suggests this event means that an active thread was interrupted, which seems to be supported by the fact that after the interrupted thread, the thread pool was increased.

[2/13/18 22:04:41:848 CST] 00000081 ThreadPool    I   WSVR0630I: Growable thread pool "SoapConnectorThreadPool" has been expanded beyond its initially-defined maximum capacity.  The pool size is currently "6".

The interrupted thread would have then been closed, which may produce unpredicible issues with the app.