zentol commented on a change in pull request #13163:
URL: https://github.com/apache/flink/pull/13163#discussion_r471631455
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File path:
flink-runtime/src/main/java/org/apache/flink/runtime/management/JMXService.java
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@@ -85,6 +86,9 @@ private static JMXServer
startJMXServerWithPortRanges(Iterator<Integer> ports) {
while (ports.hasNext() && successfullyStartedServer == null) {
JMXServer server = new JMXServer();
int port = ports.next();
+ if (port == 0) { // try poke with a random port when
port is set to zero
Review comment:
That's a fair concern, and it does make me wonder whether we shouldn't
just add a retry to the port poking approach; on average we'll likely end up
with fewer attempts.
Nevertheless, I still thought about how we could alleviate the concern:
We could use a custom iterator that is not simply iterating over the port
range, but also jumping into other port blocks.
So instead of checking `1, 2, 3, ..., 65000` we do ` 1000, 2000, 3000, ...,
65000, 1, 1001, 2001, ...`; i would think it is more likely that we run into a
completely used port block (e.g., 8000-9000) than the first N ports in each
block being used.
We can make the blocks arbitrarily small (e.g., 100), and the iterator
implementation should be fairly simple.
```
non-iterator solution:
port = START // this could even be random value between 1 and BLOCK_SIZE
while (port != SOME_END_CRITERIA_PORT):
if (!canCreateJMXServer(port)):
port = port + BLOCK_SIZE
if port > MAX:
port = (port + 1) % MAX
```
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