RFR: 8195129: System.load() fails to load from unicode paths [v2]

[Maxim Kartashev]

On Thu, 27 May 2021 05:13:44 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Maxim Kartashev has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:
>> 
>>   8195129: System.load() fails to load from unicode paths
>
> src/hotspot/os/windows/os_windows.cpp line 1541:
> 
>> 1539: void * os::dll_load(const char *utf8_name, char *ebuf, int ebuflen) {
>> 1540:   LPWSTR utf16_name = NULL;
>> 1541:   errno_t err = convert_UTF8_to_UTF16(utf8_name, &utf16_name);
> 
> Do you have any figures on the cost of this additional conversion in relation to startup time?
> 
> I'm already concerned to see that we have to perform each conversion twice via MultiByteToWideChar/WideCharToMultiByte, once to get the size and then to actually get the characters! This seems potentially very inefficient.

I measured time spend converting the library path name relative to the overall time of a (successful) `os::dll_load()` call. It varies between a fraction of a percent to ~3% (see below for the actual data from a `release` build). I'll defer to your expertise wrt to these numbers.

What can be done here (without changing os::dll_load() API) is to have a "fast path" for ascii-only path names, in which case no conversion is necessary, and a "slow path" for all the rest. This will complicate things a bit, but not by much, I believe. I am certainly willing to give that a try. Let me know what do you think.



./build/windows-x86_64-server-release/images/jdk/bin/java -jar ./build/windows-x86_64-server-fastdebug/images/jdk/demo/jfc/SwingSet2/SwingSet2.jar
0.050% for C:\cygwin64\home\maxim\work\OpenJDK\jdk\build\windows-x86_64-server-release\images\jdk\bin\jimage.dll
2.273% for C:\cygwin64\home\maxim\work\OpenJDK\jdk\build\windows-x86_64-server-release\images\jdk\bin\java.dll
0.177% for C:\cygwin64\home\maxim\work\OpenJDK\jdk\build\windows-x86_64-server-release\images\jdk\bin\net.dll
0.541% for C:\cygwin64\home\maxim\work\OpenJDK\jdk\build\windows-x86_64-server-release\images\jdk\bin\nio.dll
0.359% for C:\cygwin64\home\maxim\work\OpenJDK\jdk\build\windows-x86_64-server-release\images\jdk\bin\zip.dll
3.186% for C:\cygwin64\home\maxim\work\OpenJDK\jdk\build\windows-x86_64-server-release\images\jdk\bin\jimage.dll
0.075% for C:\cygwin64\home\maxim\work\OpenJDK\jdk\build\windows-x86_64-server-release\images\jdk\bin\awt.dll
0.232% for C:\cygwin64\home\maxim\work\OpenJDK\jdk\build\windows-x86_64-server-release\images\jdk\bin\freetype.dll
0.136% for C:\cygwin64\home\maxim\work\OpenJDK\jdk\build\windows-x86_64-server-release\images\jdk\bin\fontmanager.dll
0.170% for C:\cygwin64\home\maxim\work\OpenJDK\jdk\build\windows-x86_64-server-release\images\jdk\bin\javajpeg.dll

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PR: https://git.openjdk.java.net/jdk/pull/4169