Open code review for 8061999 Enhance VM option parsing to allow options to be specified
Ron Durbin
ron.durbin at oracle.com
Thu Jul 16 20:00:00 UTC 2015
I will file it and thanks for the "r" review.
>-----Original Message-----
>From: gerard ziemski
>Sent: Thursday, July 16, 2015 1:48 PM
>To: Ron Durbin; hotspot-runtime-dev at openjdk.java.net
>Subject: Re: Open code review for 8061999 Enhance VM option parsing to allow options to be specified
>
>hi Ron,
>
>I have no more comments, just one question: you say "A future
>enhancement will be to refactor the options file processing to grow
>memory like the environment variables do now." - is that enhancement
>filed yet?
>
>Please consider this reviewed with small "r".
>
>
>cheers
>
>
>On 07/14/2015 05:21 PM, Ron Durbin wrote:
>> Gerard,
>>
>> Thanks for your time in reviewing the code and providing comments.
>> My responses to your comments inline below:
>>
>>
>>> -----Original Message-----
>>> From: Gerard Ziemski
>>> Sent: Tuesday, June 23, 2015 1:53 PM
>>> To: hotspot-runtime-dev at openjdk.java.net
>>> Cc: Ron Durbin
>>> Subject: Re: Open code review for 8061999 Enhance VM option parsing to allow options to be specified
>>>
>>> hi Ron,
>>>
>>> I'm sending you partial feedback, since I am starting to get a bit tired. I will spend more time reviewing
>your
>>> webrev tomorrow, but here is what I have so far:
>>>
>>> ---
>>> src/share/vm/utilities/globalDefinitions.hp
>>>
>>> 1. Should we name the method "is_white()", not "iswhite()" since it's part of our code base? But then since
>it's
>>> a macro, shouldn't it actually be "IS_WHITE()" ?
>>> ---
>>> src/share/vm/runtime/arguments.hpp
>>> [
>>
>> [Ron] While researching my answer to this comment, I realized
>> that I should have used the already existing isspace() function
>> instead of creating the iswhite() macro. Will fix.
>>
>>> 1.
>>>
>>> All the arguments in alloc_JVM_options_list(), copy_JVM_options_from_buf() and parse_JVM_options_file() use
>>> underscores in the arguments names except for merge_JVM_options_file(). I think the merge_JVM_options_file()
>>> should be:
>>>
>>> + static jint merge_JVM_options_file(const struct JavaVMInitArgs *args_in,
>>> + struct JavaVMInitArgs **args_out);
>>>
>>
>> [Ron] This one is a reasonable clean up
>>
>>> ---
>>> src/share/vm/runtime/arguments.cpp
>>>
>>> 1. Why do FreeVMOptions, DumpVMOptions, DumpVMOption and DumpOption start with capital letters? Shouldn't
>their
>>> names start with a lower case letter?
>>>
>> [Ron] This one is a reasonable clean up
>>
>>> 2. Line 4306. The pattern in Arguments::parse() seems to be to print out error message and return the error
>>> value if something goes wrong, but we do vm_exit(1) instead?
>>>
>>
>> [Ron ] The cases that will trigger this exit on fail are extreme:
>> - missing or otherwise in accessible options files
>> - Un-parsable options file, too big, too many options, nonwhite space terminated options
>> - Unable to allocate memory for options files processing
>>
>>> 3. Line 4309. I was told that when it comes to NULL pointer check we should do (NULL == args), not the other
>way
>>> around.
>>>
>> [Ron] This one is a reasonable clean up
>>
>>> 4. Line 4375. Don't we need FreeVMOptions() here? Line 4382 as well?
>>
>>
>> [Ron] Gerard this one is a reasonable clean up
>>
>>> 5. Question. Why do we need N_MAX_OPTIONS?
>>
>> [Ron] Until recently N_MAX_OPTIONS applied to environment variables too
>> N_MAX_OTIIONS is used to limit the number of options and thus the memory allocated.
>> A future enhancement will be to refactor the options file processing to grow memory like the
>> environment variables do now.
>>
>>> 6. Question. Why do we need OPTION_BUFFER_SIZE? Can't we use "int bytes_needed = fseek(stream, 0, SEEK_END);
>>> rewind(stream)" and have the code dynamically allocate memory without hard coded limits?
>>>
>> [Ron>] Until recently OPTION_BUFFER_SIZE applied to environment variables too. \
>> OPTION_BUFFER_SIZE is used to limit the memory allocated for reading the options.
>> A future enhancement will be to refactor the options file processing to grow memory like the
>> environment variables do now.
>>
>>
>>> 7. Line 3965. Can that comparison ever succeed? "read()" will not read more bytes (only less) than as
>specified
>>> by "bytes_alloc" and if it did, we would overwrite memory since our buf is only "bytes_alloc" big.
>>>
>> [Ron>] Yes that comparison can succeed. We only support an
>> options file that is <= OPTION_BUFFER_SIZE bytes in
>> size.
>>
>> We allocate a read buffer that is OPTION_BUFFER_SIZE + 1
>> bytes in size for two reasons:
>>
>> 1) to have space for a NULL terminator when the
>> options file is the maximum number of bytes
>> in length
>> 2) easy detection of an options file that is too large;
>> we try to read OPTION_BUFFER_SIZE + 1 bytes. If we
>> succeed, then the file is too big.
>>
>>
>>>
>>> cheers
>>>
>>>
>>> On 6/22/2015 7:52 AM, Ron Durbin wrote:
>>> Webrev URL:
>>> http://cr.openjdk.java.net/~rdurbin/8061999_OCR0_JDK9_webrev
>>>
>>>
>>> RFE request:
>>> https://bugs.openjdk.java.net/browse/JDK-8061999
>>>
>>> This RFE allows a file to be specified that holds VM Options that
>>> would otherwise be specified on the command line or in an environment variable.
>>> Only one options file may be specified on the command line and no options file
>>> may be specified in either of the following environment variables
>>> "JAVA_TOOL_OPTIONS" or "_JAVA_OPTIONS".
>>>
>>> The options file feature supports all VM options currently supported on
>>> the command line, except the options file option. The option to specify an
>>> options file is "-XX:VMOptionsFile=<Filename>".
>>> The options file feature supports an options file up to 1024 bytes in size
>>> and up to 64 options.
>>>
>>> This feature has been tested on:
>>> OS:
>>> Solaris, MAC, Windows, Linux
>>> Tests:
>>> Manual unit tests
>>> JPRT with -testset hotspot (including the SQE proposed test coverage for this feature.)
>>>
>>>
>>>
>>
>
More information about the hotspot-runtime-dev
mailing list