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Latency Histogram


Endpoint Description
/monitor/proxy_handshake_delay Latency of the TLS handshake
/monitor/proxy_handshake_full_delay Latency of the TLS full handshake
/monitor/proxy_handshake_resume_delay Latency of the TLS abbreviated handshake
/monitor/proxy_delay Forwarding Latency for the GET requests
/monitor/proxy_post_delay Forwarding Latency for the POST requests


Metric Description
Interval Statistical period (second)
ProgramName Program name
KeyPrefix Key prefix
CurrTime Start time of current statistics
Current Latency histgram for current statistics
PastTime Start time of last statistics
Past Latency histgram for last statistics

Special Notes for Prometheus format

BFE can expose metrics in various formats.

Unlike other formats, in the Prometheus format latency histogram, counter for a bucket with lager upper bound will include the number of events in buckets with smaller upper bound. See Histogram in Prometheus document for more detail.


  • proxy_handshake_delay_Past_bucket{le="1000"} is counter of handshakes with <= 1000 ms delay in last statistic interval
  • proxy_handshake_delay_Past_bucket{le="2000"} is counter of handshakes with <= 2000 ms delay (includes those with <=1000 ms delay) in last statistic interval
  • proxy_handshake_delay_Past_bucket{le="+Inf"} is counter of handshakes with less than infinity (equals total count) in last statistic interval. It is equal to proxy_handshake_delay_Past_count.