RFR: 8269258: java/net/httpclient/ManyRequestsLegacy.java failed with connection timeout

[Daniel Fuchs]

The three tests:

test/jdk/java/net/httpclient/ManyRequests.java
test/jdk/java/net/httpclient/ManyRequests2.java
test/jdk/java/net/httpclient/ManyRequestsLegacy.java


have been observed failing intermittently with ConnectException on windows 10 machines in our CI.
These tests open 20 concurrent requests each, and the suspicion is that when these tests run concurrently on the same machine they may cross some OS throttling threshold that causes the connection to be rejected.

The tests had a built-in mechanism to throttle the number of requests running concurrently, but it was not used.
The fix is to enable this mechanism on windows, limiting the concurrency to 10 requests, if the first run of the test fails with a ConnectException. 

With this in place I am no longer observing any failure (was 1 to  3 failures for every 50 runs before)

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Commit messages:
 - 8269258: java/net/httpclient/ManyRequestsLegacy.java failed with connection timeout

Changes: https://git.openjdk.java.net/jdk/pull/6740/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6740&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8269258
  Stats: 269 lines in 3 files changed: 146 ins; 14 del; 109 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6740.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6740/head:pull/6740

PR: https://git.openjdk.java.net/jdk/pull/6740