jdk11 AIX PollsetSelector implementation #1652

Sreekala-Gopakumar · 2026-01-14T15:38:44Z

#1648

New parameter related to NIO selector provider added for -Djava.nio.channels.spi.SelectorProvider system property.

Closes #1648
Signed-off-by: Sreekala Gopakumar [email protected]

Sreekala-Gopakumar · 2026-01-14T15:39:41Z

Jenkins doc stage

Sreekala-Gopakumar · 2026-01-14T15:59:30Z

@pshipton - I have updated the topics. Please check and let me know if the changes are ok. Thanks!

pshipton · 2026-01-14T16:16:36Z

docs/configuring.md


+## ![Start of content that applies to Java 11 (LTS)](cr/java11.png) Configuring the NIO selector provider (AIX only)

+In the 0.57.0 release, a new New Input/Output (NIO) channels selector provider, which is based on pollset system facility, is implemented on AIX. NIO selectors are used for scalable I/O operations, allowing a single thread to monitor multiple channels. The pollset facility is an AIX-specific system call that efficiently handles multiple file descriptors. The new NIO selector provider configuration provides significant performance benefits when reading from, writing to, or managing a steady number of network sockets.


channels -> channel
based on pollset -> based on the pollset
Same changes apply to version0.57.md

I suggest removing "steady" from the final sentence here.

@keithc-ca - Would it better to say "...managing multiple network sockets"?

That works for me.

pshipton · 2026-01-14T16:18:20Z

docs/configuring.md


+In the 0.57.0 release, a new New Input/Output (NIO) channels selector provider, which is based on pollset system facility, is implemented on AIX. NIO selectors are used for scalable I/O operations, allowing a single thread to monitor multiple channels. The pollset facility is an AIX-specific system call that efficiently handles multiple file descriptors. The new NIO selector provider configuration provides significant performance benefits when reading from, writing to, or managing a steady number of network sockets.

+This feature is available only optionally at run time and not by default. You can configure it by specifying the new parameter `sun.nio.ch.PollsetSelectorProvider` in the `-Djava.nio.channels.spi.SelectorProvider` system property on the command line.


"only" can be removed.

keithc-ca · 2026-01-14T16:32:17Z

docs/version0.57.md


+### ![Start of content that applies to Java 11 (LTS)](cr/java11.png) A new NIO selector provider implementation is available for AIX
+
+A new New Input/Output (NIO) channel selector provider, which is based on the pollset system facility, is implemented on AIX. The new implementation provides significant performance benefits when reading from, writing to, or managing a steady number of network sockets.


Suggest removing "steady" here as well.

Would it better to say "...managing multiple network sockets"?

Sreekala-Gopakumar · 2026-01-14T16:57:01Z

Jenkins doc stage

Sreekala-Gopakumar · 2026-01-14T17:02:29Z

@pshipton @keithc-ca - I have changed the sentence to "...managing multiple network sockets". Hope that is ok.

Also, I have assumed that the -Djava.nio.channels.spi.SelectorProvider system property is not a new property. It is the parameter sun.nio.ch.PollsetSelectorProvider for this system property that is the new change. I have documented based on this assumption.

Btw, I don't see a separate topic for the -Djava.nio.channels.spi.SelectorProvider system property. This is not documented. Should it be documented? Thanks!

zl-wang

LGTM

keithc-ca · 2026-01-14T18:11:24Z

docs/configuring.md


+In the 0.57.0 release, a new New Input/Output (NIO) channel selector provider, which is based on the pollset system facility, is implemented on AIX. NIO selectors are used for scalable I/O operations, allowing a single thread to monitor multiple channels. The pollset facility is an AIX-specific system call that efficiently handles multiple file descriptors. The new NIO selector provider configuration provides significant performance benefits when reading from, writing to, or managing multiple network sockets.

+This feature is available optionally at run time and not by default. You can configure it by specifying the new parameter `sun.nio.ch.PollsetSelectorProvider` in the `-Djava.nio.channels.spi.SelectorProvider` system property on the command line.


I suggest "value" would be better than "parameter" here.

keithc-ca · 2026-01-14T18:11:50Z

docs/version0.57.md

+
+A new New Input/Output (NIO) channel selector provider, which is based on the pollset system facility, is implemented on AIX. The new implementation provides significant performance benefits when reading from, writing to, or managing multiple network sockets.
+
+This feature is available optionally at run time and not by default. You can configure it by specifying the new parameter `sun.nio.ch.PollsetSelectorProvider` in the `-Djava.nio.channels.spi.SelectorProvider` system property on the command line.


Again, parameter -> value.

pshipton · 2026-01-14T18:38:37Z

I don't see a separate topic for the -Djava.nio.channels.spi.SelectorProvider system property. This is not documented. Should it be documented?

It's documented in OpenJDK API documentation:
https://docs.oracle.com/javase/8/docs/api/java/nio/channels/spi/SelectorProvider.html

pshipton · 2026-01-14T18:42:39Z

docs/configuring.md


+## ![Start of content that applies to Java 11 (LTS)](cr/java11.png) Configuring the NIO selector provider (AIX only)

+In the 0.57.0 release, a new New Input/Output (NIO) channel selector provider, which is based on the pollset system facility, is implemented on AIX. NIO selectors are used for scalable I/O operations, allowing a single thread to monitor multiple channels. The pollset facility is an AIX-specific system call that efficiently handles multiple file descriptors. The new NIO selector provider configuration provides significant performance benefits when reading from, writing to, or managing multiple network sockets.


This contains "new New", I think "new" can be removed. Also it would read better as:

a New Input/Output (NIO) channel selector provider is implemented on AIX, which is based on the pollset system facility.

Even for "new NIO" the "new" can be removed. It's new today, but it won't be in 3 months.

The "new New" sequence made me pause. Perhaps it would read better as:

an NIO (New Input/Output) channel selector

This contains "new New", I think "new" can be removed. Also it would read better as:

a New Input/Output (NIO) channel selector provider is implemented on AIX, which is based on the pollset system facility.

@pshipton @keithc-ca - Yes, this "new New" did make me pause too, but I was not sure whether there were any other NIO channel provider or not. I will change this.

@pshipton - But, the "a New Input/Output (NIO) channel selector provider is implemented on AIX, which is based on the pollset system facility" might be misinterpreted as that the AIX itself is based on the pollset system facility, rather than the NIO provider. The " which is based on the pollset..." should be near "...provider" because that sentence modifies the "provider" not "AIX". (I am assuming that it is the NIO channel security provider that is based on the pollset facility.) I would strongly recommend to keep the sentence as

"...a New Input/Output (NIO) channel selector provider, which is based on the pollset system facility, is implemented on AIX."

The "new New" sequence made me pause. Perhaps it would read better as:

an NIO (New Input/Output) channel selector

As a rule, we usually provide the expanded form first and then place the abbreviation in the brackets. I have changed the sentence to read

...a New Input/Output (NIO) channel selector provider, which is based on the pollset system facility, is implemented on AIX.

eclipse-openj9#1648 New parameter related to NIO selector provider added for `-Djava.nio.channels.spi.SelectorProvider` system property. Review comment incorporated. Closes eclipse-openj9#1648 Signed-off-by: Sreekala Gopakumar [email protected]

Sreekala-Gopakumar · 2026-01-15T02:06:47Z

Jenkins doc stage

keithc-ca · 2026-01-15T14:09:39Z

docs/version0.57.md

+
+A New Input/Output (NIO) channel selector provider, which is based on the pollset system facility, is implemented on AIX. The new implementation provides significant performance benefits when reading from, writing to, or managing multiple network sockets.
+
+This feature is available optionally at run time and not by default. You can configure it by specifying the new value `sun.nio.ch.PollsetSelectorProvider` in the `-Djava.nio.channels.spi.SelectorProvider` system property on the command line.


Perhaps a nit, but the system property name does not start with -D.

The phrase "optionally at run time" suggests that the choice can be made after the VM starts which is not the case.

So, what is the correct system property name? Also, in our existing documents, all the system properties have "-D". Is this system property different?

Regarding the 2nd change, how about:

This feature is available at run time only and not by default.

The system property name is "java.nio.channels.spi.SelectorProvider". I think we should use the same style as in https://github.com/eclipse-openj9/openj9-docs/blob/master/docs/version0.56.md which says

the format of the java.vm.version system property value

or https://github.com/eclipse-openj9/openj9-docs/blob/master/docs/vgclog.md which says

the system property file.encoding is set to bestfit936

It might look like this: This feature is not enabled by default; to enable it, set the value of the system property java.nio.channels.spi.SelectorProvider to sun.nio.ch.PollsetSelectorProvider.

@keithc-ca - Should we also specify that this is possible at run time only and not after the VM starts?

This feature is not enabled by default. To enable it, set the value of the system property java.nio.channels.spi.SelectorProvider to sun.nio.ch.PollsetSelectorProvider at run time.

Also, should -Djava.nio.channels.spi.SelectorProvider=sun.nio.ch.PollsetSelectorProvider be changed or is it correct?

Sreekala-Gopakumar self-assigned this Jan 14, 2026

Sreekala-Gopakumar added this to the Release 0.57 (Java 8, 11, 17, 21, 25) Jan refresh milestone Jan 14, 2026

pshipton reviewed Jan 14, 2026

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Sreekala-Gopakumar force-pushed the 1648AIXPollset branch from 21a40a0 to 3972237 Compare January 14, 2026 16:24

keithc-ca reviewed Jan 14, 2026

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Sreekala-Gopakumar force-pushed the 1648AIXPollset branch from 3972237 to 1275de5 Compare January 14, 2026 16:56

zl-wang approved these changes Jan 14, 2026

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keithc-ca requested changes Jan 14, 2026

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pshipton reviewed Jan 14, 2026

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jdk11 AIX PollsetSelector implementation

83c1904

eclipse-openj9#1648 New parameter related to NIO selector provider added for `-Djava.nio.channels.spi.SelectorProvider` system property. Review comment incorporated. Closes eclipse-openj9#1648 Signed-off-by: Sreekala Gopakumar [email protected]

Sreekala-Gopakumar force-pushed the 1648AIXPollset branch from 1275de5 to 83c1904 Compare January 15, 2026 01:26

pshipton approved these changes Jan 15, 2026

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keithc-ca reviewed Jan 15, 2026

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		## ![Start of content that applies to Java 11 (LTS)](cr/java11.png) Configuring the NIO selector provider (AIX only)

		In the 0.57.0 release, a new New Input/Output (NIO) channels selector provider, which is based on pollset system facility, is implemented on AIX. NIO selectors are used for scalable I/O operations, allowing a single thread to monitor multiple channels. The pollset facility is an AIX-specific system call that efficiently handles multiple file descriptors. The new NIO selector provider configuration provides significant performance benefits when reading from, writing to, or managing a steady number of network sockets.


		In the 0.57.0 release, a new New Input/Output (NIO) channels selector provider, which is based on pollset system facility, is implemented on AIX. NIO selectors are used for scalable I/O operations, allowing a single thread to monitor multiple channels. The pollset facility is an AIX-specific system call that efficiently handles multiple file descriptors. The new NIO selector provider configuration provides significant performance benefits when reading from, writing to, or managing a steady number of network sockets.

		This feature is available only optionally at run time and not by default. You can configure it by specifying the new parameter `sun.nio.ch.PollsetSelectorProvider` in the `-Djava.nio.channels.spi.SelectorProvider` system property on the command line.


		### ![Start of content that applies to Java 11 (LTS)](cr/java11.png) A new NIO selector provider implementation is available for AIX

		A new New Input/Output (NIO) channel selector provider, which is based on the pollset system facility, is implemented on AIX. The new implementation provides significant performance benefits when reading from, writing to, or managing a steady number of network sockets.


		In the 0.57.0 release, a new New Input/Output (NIO) channel selector provider, which is based on the pollset system facility, is implemented on AIX. NIO selectors are used for scalable I/O operations, allowing a single thread to monitor multiple channels. The pollset facility is an AIX-specific system call that efficiently handles multiple file descriptors. The new NIO selector provider configuration provides significant performance benefits when reading from, writing to, or managing multiple network sockets.

		This feature is available optionally at run time and not by default. You can configure it by specifying the new parameter `sun.nio.ch.PollsetSelectorProvider` in the `-Djava.nio.channels.spi.SelectorProvider` system property on the command line.


		A New Input/Output (NIO) channel selector provider, which is based on the pollset system facility, is implemented on AIX. The new implementation provides significant performance benefits when reading from, writing to, or managing multiple network sockets.

		This feature is available optionally at run time and not by default. You can configure it by specifying the new value `sun.nio.ch.PollsetSelectorProvider` in the `-Djava.nio.channels.spi.SelectorProvider` system property on the command line.

jdk11 AIX PollsetSelector implementation #1652

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jdk11 AIX PollsetSelector implementation #1652

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