huangyiminghappy edited a comment on issue #2306:
URL: https://github.com/apache/rocketmq/issues/2306#issuecomment-699800047
> Yes, the default `SelectorProvider` will choose the right `Selector` based
on the system, as for Linux, it will use `EPollSelectorProvider` if the kernel
is 2.6 or newer otherwise it will choose `PollSelectorProvider`.
> But as the the JDK api says, users can specify their own SelectorProvider:
>
> ```
> The first invocation of this method locates the default provider object as
follows:
>
> If the system property java.nio.channels.spi.SelectorProvider is defined
then it is taken to be the fully-qualified name of a concrete provider class.
The class is loaded and instantiated; if this process fails then an unspecified
error is thrown.
>
> If a provider class has been installed in a jar file that is visible to
the system class loader, and that jar file contains a provider-configuration
file named java.nio.channels.spi.SelectorProvider in the resource directory
META-INF/services, then the first class name specified in that file is taken.
The class is loaded and instantiated; if this process fails then an unspecified
error is thrown.
>
> Finally, if no provider has been specified by any of the above means then
the system-default provider class is instantiated and the result is returned.
>
> Subsequent invocations of this method return the provider that was
returned by the first invocation.
> ```
>
> So, IMHO, if it is the purpose of RocketMQ to disable user-specified
Selector and use `EPollSelectorProvider` regardless of user configuration, use
only `Selector.open()` would not work.
I agree with some of your views，but i think that,if the code Clearly
indicate the use like `if (isLinuxPlatform()) {
try {
final Class<?> providerClazz =
Class.forName("sun.nio.ch.EPollSelectorProvider");`
i think the use like this,The user has no choice,The effect is that the user
uses EPollSelectorProvider on the linux platform, if the linux version is less
than 2.6,we can not require user use 'EPollSelectorProvider', so i think some
code can use Selector.open() instead, and why user must use
EPollSelectorProvider in linux as the only choose ? may be they can use custom
selector,so i think we need clear some unnecessory code
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