Limit amount of native memory used for NIO buffers

[Praveen2112]

Set the default value of jdk.nio.maxCachedBufferSize to 2MB. If we did not set this JVM would take the entire System memory as the maximumbuffer size and it will result in increase in non-heap memory for the JVM process.

[Praveen2112]

@findepi Have added the default value as 2MB.

[findepi]

@Praveen2112 thanks for the PR.
Please change commit title (the first line) to something like Limit amount of native memory used for NIO buffers.

[findepi]

@Praveen2112 please add this also after https://github.com/prestosql/presto/blob/cdc3f3420e451ea65b3e2bbc1fa8561f9fbe9738/presto-product-tests/conf/presto/etc/jvm.config#L15

@martint if you're OK with this change, I would also recommend adding this to https://github.com/prestosql/presto/blob/9622c3f959f828f3614790c44ab5d545d5cea5ef/presto-docs/src/main/sphinx/installation/deployment.rst#jvm-config

[martint]

We used to set this to 1MB at FB.

[martint]

if you're OK with this change

I'm ok with it, but in general, we should try to figure out why this is happening. The setting is a bandaid to a problem that can be solved by fixing the calling code to size buffers more carefully.

[Praveen2112]

@findepi Have updated the commit message.
@martint , @findepi Currently we have a check for the Page size when pushing to the OutputBuffer (IIRC the max is 1MB) but we didn't have any such limits for the ConnectorSplit so if we add some restrictions on the split size then we could have a control over the buffer size and usage of native memory.

[findepi]

@Praveen2112 please also update
https://github.com/prestosql/presto/blob/9622c3f959f828f3614790c44ab5d545d5cea5ef/presto-docs/src/main/sphinx/installation/deployment.rst#jvm-config

[Praveen2112]

@findepi Thanks for pointing it out. I have updated it.