If you are somehow still using axis 1.4 framework as your web service client implementation, you may suffer from some thread safety problems.
We have faced one of these, and when we researched about it, it was specified as a bug also in axis community => https://issues.apache.org/jira/browse/AXIS-2647
The problem seems to be an infinite loop problem due to a concurrent access to a nonsynchronized object. Threads running the method getFieldNameForElement cannot leave the method, causing threads in the application server to run out and also %100 CPU problem in the machine.
Applying the patch given in this link resolves the issue.
The patch simply consists of making the acces to fieldElementMap(HashMap instance) synchronized in getFieldNameForElement method of TypeDesc.java class;
