code: public static void cleanObsolete() {
          HandlerThreadFactory.getWriteLogThreadHandler().post(new Runnable() {
              @Override
              public void run() {
                  long now = System.currentTimeMillis();
                  File[] f = BlockCanaryInternals.getLogFiles();
                  if (f != null && f.length > 0) {
                      synchronized (SAVE_DELETE_LOCK) {
                          for (File aF : f) {
                              if (now - aF.lastModified() > OBSOLETE_DURATION) {
                                  aF.delete();
                              }
                          }
                      }
                  }
              }
          });
      }
docs: Delete obsolete log files, which is by default 2 days.