[shinseongsu]

BasicHttpClientConnectionManager still builds its id with String.format("ep-%010d", ...). #352 replaced the same pattern with PrefixedIncrementingId in ExecSupport and in both pooling connection managers, but this one was left out. This switches it to PrefixedIncrementingId("ep-") as well, so all three connection managers generate ids the same way. The format stays ep- followed by 10 digits.

Benchmark

JMH, -prof gc, 2 forks x 5 iterations, Apple M4 Pro. Benchmark source: String.format("ep-%010d", counter.getAndIncrement()) vs PrefixedIncrementingId.getNextId().

Time per id (ns/op, lower is better)

JDK	String.format	PrefixedIncrementingId	Speedup
8u512	327.1 ± 5.4	16.9 ± 0.3	19.4x
11.0.28	256.0 ± 18.4	13.5 ± 1.1	18.9x
17.0.16	307.6 ± 3.6	12.9 ± 0.5	23.9x
21.0.10	230.6 ± 3.3	12.0 ± 0.3	19.2x
25.0.1	97.9 ± 11.3	11.2 ± 0.3	8.7x

xychart-beta
    title "ns/op (bar: String.format, line: PrefixedIncrementingId)"
    x-axis ["JDK 8", "JDK 11", "JDK 17", "JDK 21", "JDK 25"]
    y-axis "ns/op" 0 --> 350
    bar [327.1, 256.0, 307.6, 230.6, 97.9]
    line [16.9, 13.5, 12.9, 12.0, 11.2]

Loading

Allocation per id (B/op, lower is better)

JDK	String.format	PrefixedIncrementingId	Reduction
8u512	1304	136	9.6x
11.0.28	724	88	8.2x
17.0.16	1416	88	16.1x
21.0.10	656	88	7.5x
25.0.1	498	88	5.7x

xychart-beta
    title "B/op (bar: String.format, line: PrefixedIncrementingId)"
    x-axis ["JDK 8", "JDK 11", "JDK 17", "JDK 21", "JDK 25"]
    y-axis "B/op" 0 --> 1500
    bar [1304, 724, 1416, 656, 498]
    line [136, 88, 88, 88, 88]

Loading

JDK 8 was measured with JMH 1.36, since the 1.37 GC profiler reports 0 B/op there. The other JDKs use 1.37.

The id is created once per manager instance, so this only really shows up when a client is created per request. It's mostly a consistency fix.

Notes

• Ids now start at ep-0000000001 instead of ep-0000000000, the same as the pooling managers. The id is only used in log output.
• PrefixedIncrementingId is backed by an AtomicLong, so uniqueness under concurrent construction is unchanged.
• mvn -pl httpclient5 verify passes (1113 tests, checkstyle, japicmp).