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Date: Sat, 30 Jul 2022 12:07:00 +0200
Message-ID: <CANMwmbOz6uaD3BHF8b57KRAGyNE7QfspbdKrE_=-2_xG5o6SkA@mail.gmail.com>
To: Oleksii Bulba <oleksii.bulba@gmail.com>
Cc: PHP Internals List <internals@lists.php.net>
Content-Type: multipart/alternative; boundary="0000000000002fc7b905e502ee4d"
Subject: Re: [PHP-DEV] RFC Idea - is_json - looking for feedback
From: dev.juan.morales@gmail.com (juan carlos morales)

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El s=C3=A1b., 30 de julio de 2022 11:58, Oleksii Bulba <oleksii.bulba@gmail=
.com>
escribi=C3=B3:

> > $memoryAfter =3D memory_get_usage(true) / 1024 / 1024;
>
> I see that you used `memory_get_usage` that shows memory usage at the tim=
e
> of the function call.
> As far as I understand, your function does not return any value,
> so I suspect that it is obvious that the memory usage after the function
> call is the same as before.
> But what is the actual memory usage during the function call?
> Can you run the same benchmark but with `memory_get_peak_usage` function
> to see how your function uses memory?
>
> # $memoryAfter =3D  memory_get_peak_usage(true) / 1024 / 1024;
>
> Also, I'm concerned if it would be better to name the function
> `is_json_valid`?
>
> On Sat, Jul 30, 2022 at 10:37 AM juan carlos morales <
> dev.juan.morales@gmail.com> wrote:
>
>> Just want to clarify that when I mentioned the use of memory, I wrote do=
wn
>> the function "memory_get_usage()", which basically gives us the memory
>> handle by php that is related to the memory_limit INI setting.
>>
>> Now I will provide a benchmark I have done really quick:
>>
>> # Code used (I have the implementation of is_json() done already)
>>
>> <?php
>> // make sure you set your memory limit to -1 before running this code
>> // Here we create a very very very big json string, really big
>> $limit =3D 1000000;
>> $jsonString =3D '{ "test": { "foo": "bar" },';
>>
>> for ($i=3D0; $i < $limit; $i++) {
>>   $jsonString .=3D " \"test$i\": { \"foo\": { \"test\" : { \"foo\" :  {
>> \"test\" : { \"foo\" : \"bar\" }}}}},";
>> }
>>
>> $jsonString .=3D ' "testXXXX": { "foo": "replaceme" } }';
>> //{ "test" : { "foo" : "bar" }}}
>>
>> $memoryBefore =3D memory_get_usage(true) / 1024 / 1024;
>> echo "Megas used before call: " . $memoryBefore . PHP_EOL;
>>
>> $start =3D microtime(true);
>>
>> json_decode($jsonString, null, $limit, 0);
>> //<------------------ un/comment to show/hide results for json_decode()
>> //is_json($jsonString);
>>  //<------------------ un/comment to show/hide results for is_json()
>>
>> $memoryAfter =3D memory_get_usage(true) / 1024 / 1024;
>> echo "Megas used after call: " . $memoryAfter . PHP_EOL;
>>
>> echo "Difference: " . ($memoryAfter - $memoryBefore) . PHP_EOL;
>>
>> echo "Time: " . (microtime(true) - $start) . " seconds" . PHP_EOL;
>> return;
>>
>> # Results
>> ## json_decode()
>> Megas used before call: 79.23828125
>> Megas used after call: 3269.23828125
>> Difference: 3190
>> Time: 12.091101884842 seconds
>>
>> ## is_json()
>> Megas used before call: 79.23828125
>> Megas used after call: 79.23828125
>> Difference: 0
>> Time: 5.4537169933319 seconds
>>
>>
>> And yes, I am open to share the implementation, but after I write the RF=
C.
>>
>> Thanks for taking your time to give me a feedback.
>>
>> El s=C3=A1b, 30 jul 2022 a las 3:50, Jordan LeDoux (<jordan.ledoux@gmail=
.com>)
>> escribi=C3=B3:
>>
>> >
>> >
>> > On Fri, Jul 29, 2022 at 7:27 AM juan carlos morales <
>> > dev.juan.morales@gmail.com> wrote:
>> >
>> >> # Why this function ?
>> >>
>> >> At the moment the only way to determine if a JSON-string is valid we
>> have
>> >> to execute the json_decode() function.
>> >>
>> >> The drawback about this, is that json_decode() generates an in memory
>> an
>> >> object/array (depending on parameters) while parsing the string; this
>> >> leads
>> >> to a memory usage that is not needed (because we use memory for
>> creating
>> >> the object/array) and also can cause an error for reaching the
>> >> memory-limit
>> >> of the php process.
>> >>
>> >> Sometimes we just need to know is the string is a valid json or not,
>> and
>> >> nothing else.
>> >>
>> >
>> > You say that you have a first-pass at the implementation done. I'd be
>> > curious to see it. My initial thought was that in order to validate th=
e
>> > string, you likely need to allocate extra memory as part of the
>> validation
>> > that depends on the string size. You'd definitely save the overhead of=
 a
>> > ZVAL, but for such an object that overhead is likely negligible.
>> >
>> > So I guess my question would be: in the actual implementation that
>> lands,
>> > how much memory would this actually save compared to json_decode()? Th=
is
>> > seems like it would make the RFC tricky, as the purported benefit of t=
he
>> > RFC depends very tightly on the implementation that lands.
>> >
>> > Jordan
>> >
>>
>

Hello Jordan, thanks for the feedback.

I think the benchmark talks by itself (also for the memory Save question).
Also by the fact that in order to run it for json_decode() rhe memory limit
needs to be super high or -1 (no limit, not a good idea in production
right?)

The advantage here is to be able to parse huge strings without reaching the
memory limit set in the INI settings.

I take It as a "IF THIS IS AS GOOD AS IT SEEMS THEN YES" :D

Once again... Thanks

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