private void processingFailed(Processing processing, String errorMsg, Exception e) {
        if (e != null) {
            if (e instanceof HandledProcessingException) {
                errorMsg += ". Error message: " + e.getMessage();
                log.log(Level.WARNING, errorMsg);
                log.log(Level.FINE, "Chained exception:", e);
            } else {
                log.log(Level.WARNING, errorMsg, e);
            }
        } else {
            log.log(Level.WARNING, errorMsg);
        }

        //notify endpoint
        ProcessingEndpoint recv = ((ProcessingAccess)processing).getEndpoint();
        if (recv != null) {
            recv.processingFailed(processing, e);
        }
    }
Do some work on this processing. Must only be called from the worker thread.

@return true if this processing should be removed, false if there is more work to do on it later
@throws NoCallStackException if no CallStack has been set on this executor.
docproc/src/main/java/com/yahoo/docproc/impl/DocprocService.java