[XDCR] network usage limit setting exceeded by goxdcr process

Steps followed:

1. Create a 1x1 replication with XDCR Network usage limit set to 1 MB/sec

2. Start pumping in data using following command:

/opt/couchbase/lib/python/cbworkloadgen -i 25000000 -j -n 127.0.0.1:8091 -u Administrator -p password -s 1024

3. Use nethogs tool to monitor bandwidth consumed by goxdcr process - expectation is that xdcr process uses less than 1000 KB/sec (nethogs measures in KB/sec) always

4. But nethogs shows that goxdcr process is almost always consuming more than 1000 KB/sec - most of the times it is between 1000 - 1100 KB/sec but there are times where it goes up to 1300 KB/sec - attaching screenshots

5. bandwidth_limit is set to 1 MB/sec (1048576 b/s) as expected:

2017-05-22T03:04:40.621-07:00 INFO GOXDCR.StatsMgr: 377e0e438b862a353ef693ce733cc124/default/default_BandwidthThrottlerSvc bandwidth_limit=1048576, bandwidth_usage=733673

2017-05-22T03:04:40.623-07:00 INFO GOXDCR.StatsMgr: 377e0e438b862a353ef693ce733cc124/default/default_ThroughSeqnoTracker time_spent=1.730183ms num_vb=1024 max_sent=15 avg_sent=2 max_filtered=0 avg_filtered=0 max_failed_cr=0 avg_failed_cr=0 max_gap=0 avg_gap=0

logs collected: https://s3.amazonaws.com/bugdb/jira/may22/collectinfo-2017-05-22T103056-ns_1%40172.23.105.27.zip