4 ms·

PHP's garbage collector is ARC, unlike any other dynamic language that I know of. ARC is more performant but can introduce memory leaks via circular references

by mojuba 5y ago

PHP's garbage collector is ARC, unlike any other dynamic language that I know of. ARC is more performant but can introduce memory leaks via circular references, which is probably not a big problem for short-lived scripts anyway.

nicoburns 5y ago
Sounds optimal for PHP where 99% of scripts are short lived.
- JiNCMG 5y ago
  Which is perfect for a HTTP request.
Isinlor 5y ago
I'm not sure if you did not read what I quoted, or I misunderstand something. Yes, PHP has reference counting, but it also has specific process that kicks in to clean up circular references.
kaba0 5y ago
How is it more performant? If you have multiple threads than you will get serious atomic operation or other synchronization overhead.
- Isinlor 5y ago
  PHP is share-nothing architecture. Nobody really uses threads in mainline PHP. Whole class of problems around multi-threading, mutexes, dead locks etc. are really foreign to PHP developers.
  - kaba0 5y ago
    Yeah, I should have mentioned that in the general case RC is not more performant (otherwise threaded managed languages would use it).
housecarpenter 5y ago
Python uses ARC plus a tracing GC for dealing with cycles, same as PHP: https://devguide.python.org/garbage_collector/ https://devguide.python.org/garbage_collector/ Perl uses ARC with no tracing GC, so you have to handle cycles yourself: https://www.perlmonks.org/?node_id=1173079 https://www.perlmonks.org/?node_id=1173079 TCL uses ARC, and apparently doesn't need a tracing GC because it is impossible to create cycles in it: https://wiki.tcl-lang.org/page/Garbage+collection https://wiki.tcl-lang.org/page/Garbage+collection
Zababa 5y ago
ARC is not more performant, it's more deterministic. "regular" GCs have better throughput. RC in general also handles other resources (like files) a bit better than GC.
fooyc 5y ago
PHP has a GC since 2009 (version 5.3). Its goal is precisely to collect reference cycles.

by mojuba 5y ago

nicoburns 5y ago

Sounds optimal for PHP where 99% of scripts are short lived.

JiNCMG 5y ago
Which is perfect for a HTTP request.

Isinlor 5y ago

I'm not sure if you did not read what I quoted, or I misunderstand something. Yes, PHP has reference counting, but it also has specific process that kicks in to clean up circular references.

kaba0 5y ago

How is it more performant? If you have multiple threads than you will get serious atomic operation or other synchronization overhead.

Isinlor 5y ago
PHP is share-nothing architecture. Nobody really uses threads in mainline PHP. Whole class of problems around multi-threading, mutexes, dead locks etc. are really foreign to PHP developers.
- kaba0 5y ago
  Yeah, I should have mentioned that in the general case RC is not more performant (otherwise threaded managed languages would use it).

housecarpenter 5y ago

Python uses ARC plus a tracing GC for dealing with cycles, same as PHP: https://devguide.python.org/garbage_collector/ https://devguide.python.org/garbage_collector/ Perl uses ARC with no tracing GC, so you have to handle cycles yourself: https://www.perlmonks.org/?node_id=1173079 https://www.perlmonks.org/?node_id=1173079 TCL uses ARC, and apparently doesn't need a tracing GC because it is impossible to create cycles in it: https://wiki.tcl-lang.org/page/Garbage+collection https://wiki.tcl-lang.org/page/Garbage+collection

Zababa 5y ago

ARC is not more performant, it's more deterministic. "regular" GCs have better throughput. RC in general also handles other resources (like files) a bit better than GC.

fooyc 5y ago

PHP has a GC since 2009 (version 5.3). Its goal is precisely to collect reference cycles.