As a work around, you can shutdown OneClick and remove the existing $SPECROOT/OCLogs/client.log file.
This issue is addressed in the 10.02.01.PTF_10.2.152 patch for Spectrum 10.02.01. The following is in the release note for the 10.02.01.PTF_10.2.152 patch:
Symptom:The OC Webserver is going OutOfMemory while reading the client.log file when its size is very huge ~300MB or above.
Resolution: The OC Webserver will handle the reading of large client.log files as this solution has the optimized client.log file purging based on number of days and max entries logic in place.
Please contact CA Spectrum support for a copy of the 10.02.01.PTF_10.2.152 patch.
This issue is also scheduled to be addressed in Spectrum 10.02.02.