Ceph » rgw

RGWDataSyncShardCR should be wakened up every 20 seconds(defined by INCREMENTAL_INTERVAL) when there is no IO to rgw. But we found it is wakened up almost at every second in our production environment.
Further investigation shows that this is because of the out-band data process logic. Each time rgw receives out-band data, it will wake up the corresponding CR. But this CR will add a new timer event before it yield. With time passing, a CR will have more than one timer event, so it will be wakened up more than one time in every 20 seconds.

This problem can be reproduced as follows:
1. set rgw_data_log_num_shards = 1, debug_rgw = 20
2. `tail -f /var/log/ceph/ceph-client.rgw.1.log |grep "shard_id=0"`, this will print logs every 20 seconds
3. upload one file
4. observe results in step 2, it will print more log than before.