code: private void updateRenewalThreshold() {
          try {
              Applications apps = eurekaClient.getApplications();
              int count = 0;
              for (Application app : apps.getRegisteredApplications()) {
                  for (InstanceInfo instance : app.getInstances()) {
                      if (this.isRegisterable(instance)) {
                          ++count;
                      }
                  }
              }
              synchronized (lock) {
                  // Update threshold only if the threshold is greater than the
                  // current expected threshold or if self preservation is disabled.
                  if ((count) > (serverConfig.getRenewalPercentThreshold() * expectedNumberOfClientsSendingRenews)
                          || (!this.isSelfPreservationModeEnabled())) {
                      this.expectedNumberOfClientsSendingRenews = count;
                      updateRenewsPerMinThreshold();
                  }
              }
              logger.info("Current renewal threshold is : {}", numberOfRenewsPerMinThreshold);
          } catch (Throwable e) {
              logger.error("Cannot update renewal threshold", e);
          }
      }
docs: Updates the <em>renewal threshold</em> based on the current number of
  renewals. The threshold is a percentage as specified in
  {@link EurekaServerConfig#getRenewalPercentThreshold()} of renewals
  received per minute {@link #getNumOfRenewsInLastMin()}.