title: PersistenceException: unexpected error when rollbacking
body: <p>I am getting <strong>PersistenceException</strong> exceptiong because of the OOM error. </p>
  
  <pre><code>Exception in thread "Thread-7" java.lang.OutOfMemoryError: GC overhead limit exceeded
          at java.util.Arrays.copyOf(Arrays.java:2271)
          at java.lang.StringCoding.safeTrim(StringCoding.java:79)
          at java.lang.StringCoding.access$300(StringCoding.java:50)
          at java.lang.StringCoding$StringEncoder.encode(StringCoding.java:305)
          at java.lang.StringCoding.encode(StringCoding.java:344)
          at java.lang.String.getBytes(String.java:916)Heap dump file created [464734012 bytes in 39.704 secs]
  </code></pre>
  
  <p>I am trying to process a file having 80-100k lines. Each line will be stored as a row in the table. Every line has about 15-20 attributes. I want to understand how much memory will the DB Transaction (@Transactional) require to keep them in the entity manager and persist them at one go? 
  Batching is not feasible due to our architecture design limitations. </p>
  
  <p>Please help.</p>