RFR: 8278166: java/nio/channels/Channels/TransferTo.java timed out

[Alan Bateman]

On Fri, 3 Dec 2021 23:05:42 GMT, Brian Burkhalter <bpb at openjdk.org> wrote:

>> test/jdk/java/nio/channels/Channels/TransferTo.java line 150:
>> 
>>> 148:             try {
>>> 149:                 // create (hopefully sparse) file less than 2GB in size
>>> 150:                 final long initLen = (2*1024 - 1)*BYTES_PER_WRITE;
>> 
>> Perhaps consider clarifying the comment for the initLen calculation 
>> 
>> I do suspect the use of RandomAccessFile improves the throughput here
>
> I shall clean up the constants in the next revision.
> 
> A crude measurement showed that the execution time of `testMoreThanTwoGB()` was cut in half by this change. This sub-test is the slowest `@Test` in the test.

The general approach looks okay but the RAF to open/setLength/close is not needed. Instead change the FC.open to use WRITE and use fc.position(initLen) to set the initial position before writing.

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PR: https://git.openjdk.java.net/jdk/pull/6707