RFR: 8342995: Enhance Attach API to support arbitrary length arguments - Linux

[Serguei Spitsyn]

On Tue, 19 Nov 2024 00:04:16 GMT, Alex Menkov <amenkov at openjdk.org> wrote:

> The fix updates Linux (and server-side of macosx) implementation to support Attach API v2 (shared code and Windows implementation were introduced by #20782)
> 
> Testing: tier1,tier2,tier3,tier4,hs-tier5-svc
> manually tested backward compatibility (old tools can attach to current VMs, current tools can attach to older VMs) with jdk21 and jdk8.

src/hotspot/os/posix/attachListener_posix.cpp line 145:

> 143:  private:
> 144:   // the connection to the client
> 145:   SocketChannel _socket;

Nit: The name `_socket` is misleading. I'd suggest to rename it to `_socket_channel`.

src/hotspot/share/services/attachListener.hpp line 251:

> 249:     // Attach client can make sanity connect/disconnect.
> 250:     // In the case we get "premature EOF" error.
> 251:     // If "may_be_empty" is true, the error is not logged.

Nits or two minor suggestions:
 - replace: "In the case" => "In that case"
 - replace: "may_be_empty" => may_be_empty

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PR Review Comment: https://git.openjdk.org/jdk/pull/22223#discussion_r1879883033
PR Review Comment: https://git.openjdk.org/jdk/pull/22223#discussion_r1879876017