Bug #61168 [NEW]: fwrite() has no buffering

From: tstarling Operating system: Linux PHP version: 5.4.0RC8 Package: Streams related Bug Type: Bug Bug description:fwrite() has no buffering Description: ------------ The stream_set_write_buffer() manual entry indicates that fwrite() buffers its output. This is incorrect. For regular files, no buffering is ever done, each fwrite() call leads to a syscall. This is a performance issue, especially for extensions like the CDB handler in DBA. I have a real-world script that uses almost as much system CPU as user CPU, because each dba_insert() call leads to multiple syscalls. Test script: --------------- $f = fopen( '/tmp/blah', 'w' ); stream_set_write_buffer( $f, 8192 ); for ( $i = 0; $i < 10; $i++ ) { fwrite( $f, 'x' ); } fclose( $f ); Expected result: ---------------- strace php write-tight-loop.php ... write(3, "xxxxxxxxxx", 1) = 10 ... Actual result: -------------- write(3, "x", 1) = 1 write(3, "x", 1) = 1 write(3, "x", 1) = 1 write(3, "x", 1) = 1 write(3, "x", 1) = 1 write(3, "x", 1) = 1 write(3, "x", 1) = 1 write(3, "x", 1) = 1 write(3, "x", 1) = 1 write(3, "x", 1) = 1 -- Edit bug report at https://bugs.php.net/bug.php?id=61168&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=61168&r=trysnapshot54 Try a snapshot (PHP 5.3): https://bugs.php.net/fix.php?id=61168&r=trysnapshot53 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=61168&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=61168&r=fixed Fixed in SVN and need be documented: https://bugs.php.net/fix.php?id=61168&r=needdocs Fixed in release: https://bugs.php.net/fix.php?id=61168&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=61168&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=61168&r=needscript Try newer version: https://bugs.php.net/fix.php?id=61168&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=61168&r=support Expected behavior: https://bugs.php.net/fix.php?id=61168&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=61168&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=61168&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=61168&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=61168&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=61168&r=dst IIS Stability: https://bugs.php.net/fix.php?id=61168&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=61168&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=61168&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=61168&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=61168&r=mysqlcfg