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Comment by dhd415 | Hacker News Reader

This is really about Peachpie, an open source PHP to .NET compiler. (Edit: the title has now been updated) From the comments on the article, here's a set of benchmarks showing Peachpie with a significant performance advantage over PHP 7 in a number of benchmarks: http://www.peachpie.io/benchmarks. That said, it's still hard to get excited about PHP.

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Disclaimer: PHP core dev.

Be careful with microbenchmarks. From my experience, there tends to be very little correlation between performance improvements on microbenchmarks and real applications. If you improve performance on the microbench suite by a factor of two, you definitely will not get a factor of two on real applications -- more likely, it will be something like 2%.

Basically, if the benchmark is not testing end-to-end performance on Wordpress (or similar), then it's a useless benchmark.

The classic example of this would be that, before PHP 7, Zend spent a lot of effort trying to make PHP use JIT. It improved the results on microbenchmarks a lot, but made negligible difference to real-world code, IIRC.

Good point. In case of Peachpie microbenchmarks - that time it was the only pieces code that could be compiled ... We'll try to update benchmarks for more complex solutions.

We have a huge PHP codebase we may be interested to bring into the .NET world. I have looked at Peachpie but I wonder how well it works in the real world and what the long term prospects are.

Has anybody used it? The PHP code is full of questionable code which somehow works in PHP but I am not sure if it's possible to map PHP's behavior into .NET..

They did get WordPress at least sort of running on it. That wasn't possible with the first releases of hhvm, so it says something.

It's says they actually get WordPress running before releasing it. Not that I want to undermine project achievements, but WordPress likely going to work even on PHP 5.2.x that almost 10 years old.

My point was that WordPress is a large codebase and exercises a fair amount of php syntax and built-ins.

5.2.x is old, but that doesn't mean it's simple or easier to implement.

You're right, 7.0 for example deprecates/removes some dirty practices that are hard to implement in .NET

'Sort of running' and stable enough to deploy into production are different things. I really want this to work but I am a little nervous about committing to it.

It was running with modifications at the time, but now runs unmodified. I suggest to get in touch with the team to discuss your specific case at info at iolevel dot com.

Probably a good idea. For us this would be huge if it worked but it's pretty scary...

The previous version of Peachpie, Phalanger, had several clients with huge codebases who successfully used it to migrate their apps or interoperate with C#. Peachpie works the same way.

Disclaimer - Peachpie dev. Some of the weird PHP constructs will never work - by purpose. In such case it will be reported in compile-time or at least in run-time. However, there is always a way of slightly changing the original code to make it running on .NET.

Do you happen to have any examples?

For example one CLR limitation - `yield` cannot be in a catch block. Two workarounds - compiler can generate a crazy state machine or user can just move the PHP yield outside the catch.

Error handling is a big issue - in PHP every notice and warning can be handled in user code, in .NET we use Debug Assertions or exceptions. But .NET has threads and async which shares one thread by more requests, so in case of error we just don't know what request has to handle the error. We would have to pass some request context object to every function in runtime in order to be able to let the correct request's error_handler to handle the error - or we just assume warnings and errors should not happen and crash when it does.

Garbage Collection - for performance reasons (and sanity) we let .NET GC to do its job. But unlike PHP's GC it is undeterministic and does its job on a different thread. For now, __destruct is not handled in Peachpie yet cause there are more ways on how to simulate PHPs behavior.

Changing existing closure's $this to anything - well.. besides it would make type analysis useless, it totaly violates strong .NET method access checks.

__destruct is not called when the reference count goes to 0? This is one of the (few) features I think PHP does better than C#.

And one of the features caused memory leaking in PHP for a decade. .NET has real garbage collection, we can take advantage of it.

What PHP version is Peachpie targeting?

From this:

https://github.com/peachpiecompiler/peachpie/wiki/Peachpie-R...

Looks like PHP 5.4 and 7.1 roadmap goals have been achieved.

Though http://www.peachpie.io/about references Phalanger as the inspiration which apparently got as far as PHP 5.6.

There's also compatibility page that looks useful:

https://github.com/peachpiecompiler/peachpie/wiki/Compatibil...

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