performance
Three numbers for one process, and memory_limit reads the middle one
memory_get_usage(), memory_get_usage(true) and ps disagree about one process. What each counts, which one memory_limit reads, and why a one-megabyte string costs two.
Blog
Posts and notes.
internals
A by-reference foreach leaves a reference in every element
Walking an array with foreach ($rows as &$row) wraps every element in a zend_reference. On a million integers that is 32 MB the loop never gives back.
internals
What a PHP variable actually is
A zval is sixteen bytes, a value union and a type tag. What that tag says decides whether an assignment copies anything, what a reference costs, and which variable pays.
runtime
PHP-FPM process management in production
pm static, dynamic and ondemand, the memory ceiling nothing enforces, and how to size a pool from measurements rather than guesses.
architecture
What compiled DI containers actually buy you
Container compilation moves reflection from request time to build time. What that removes, what it costs, and when it matters.
internals
PHP arrays are not arrays
One structure serves as list, dictionary and set. Packed and hashed layouts, what each costs in memory, and when a conversion happens.
performance
OPcache, the JIT, and where time actually goes
OPcache removes compilation, not execution. The JIT reaches arithmetic-heavy code and little else. Where the remaining time lives.
performance
Benchmarking PHP without lying to yourself
Microbenchmarks measure exactly what you tell them to, which is rarely what you meant. Method, noise, and the numbers worth reporting.
internals
What happens when PHP runs your code
A request walks from the SAPI to the Zend VM — lexing, compilation to opcodes, the OPcache lookup that skips both, and execution.