A 5ms Blocking Call Took My Service From 17,189 to 549 req/s

Bitan Sarkar — Wed, 26 Aug 2026 14:12:45 +0000

A 5 millisecond blocking call. Nobody would call that slow. It passes code
review and looks fine in a trace.

On a Tomcat worker thread, my service did 17,189 req/s while an unrelated
endpoint answered in 0ms. The identical call on a Netty event loop: 549 req/s,
and that same unrelated endpoint went to 217ms.

Same call. Same machine. Same JVM. The only difference was which thread it was
allowed to occupy — so I measured it properly against real Netty 4.1 and real
embedded Tomcat 10.1.

Visit : https://bitsar.net/blog/tomcat-forgives-blocking-event-loop-doesnt

Your speed test is measuring the wrong road

Bitan Sarkar — Tue, 25 Aug 2026 17:45:39 +0000

Two people. One pays for 100 Mbps, the other for 25.
Whose video call stutters?

My connection: 62 ms idle, 1,530 ms while downloading. Seconds apart.
It speed-tests at 99 Mbps.

Your first guess is congestion. It isn't congestion.

Read the full article here: Your Speed Test Is Measuring the Wrong Road

DEV Community: Bitan Sarkar

A 5ms Blocking Call Took My Service From 17,189 to 549 req/s

Your speed test is measuring the wrong road