Profiling Module

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This XQuery Module contains various functions to test and profile code, and to dump information to standard output.

Contents

[edit] Conventions

All functions in this module are assigned to the http://basex.org/modules/prof namespace, which is statically bound to the prof prefix.
All errors are assigned to the http://basex.org/errors namespace, which is statically bound to the bxerr prefix.

[edit] Functions

[edit] prof:time

Signatures prof:time($expr as item()) as item()*
prof:time($expr as item(), $cache as xs:boolean) as item()*
prof:time($expr as item(), $cache as xs:boolean, $label as xs:string) as item()*
Summary Measures the time needed to evaluate $expr and sends it to standard error or, if the GUI is used, to the Info View.
If $cache is set to true(), the result will be temporarily cached. This way, a potential iterative execution of the expression (which often yields different memory usage) is blocked.
A third, optional argument $label may be specified to tag the profiling result.
Properties The function is non-deterministic: evaluation order will be preserved by the compiler.
Examples
  • prof:time("1 to 100000") may output 25.69 ms.
  • prof:time("1 to 100000", true()) may output 208.12 ms.

[edit] prof:mem

Signatures prof:mem($expr as item()) as item()*
prof:mem($expr as item(), $cache as xs:boolean) as item()*
prof:mem($expr as item(), $cache as xs:boolean, $label as xs:string) as item()*
Summary Measures the memory allocated by evaluating $expr and sends it to standard error or, if the GUI is used, to the Info View.
If $cache is set to true(), the result will be temporarily cached. This way, a potential iterative execution of the expression (which often yields different memory usage) is blocked.
A third, optional argument $label may be specified to tag the profiling result.
Properties The function is non-deterministic: evaluation order will be preserved by the compiler.
Examples
  • prof:mem("1 to 100000") may output 0 Bytes.
  • prof:mem("1 to 100000", true()) may output 26.678 mb.

[edit] prof:sleep

Signatures prof:sleep($ms as xs:integer) as empty-sequence()
Summary Sleeps for the specified number of milliseconds.
Properties The function is non-deterministic: evaluation order will be preserved by the compiler.

[edit] prof:human

Signatures prof:human($number as xs:integer) as xs:string
Summary Returns a human-readable representation of the specified $number.
Example
  • prof:human(16384) returns 16K.

[edit] prof:dump

Signatures prof:dump($expr as item()) as empty-sequence()
prof:dump($expr as item(), $label as xs:string) as empty-sequence()
Summary Dumps a serialized representation of $expr to STDERR, optionally prefixed with $label, and returns an empty sequence. If the GUI is used, the dumped result is shown in the Info View.
Properties In contrast to fn:trace(), the consumed expression will not be passed on.

[edit] prof:variables

Signatures prof:variables() as empty-sequence()
Summary Prints a list of all current local and global variable assignments to standard error or, if the GUI is used, to the Info View.
As every query is optimized before being evaluated, not all of the original variables may be visible in the output. Moreover, many variables of function calls will disappear because functions are inlined. Function inlining can be turned off by setting the INLINELIMIT option to 0.
Properties The function is non-deterministic: evaluation order will be preserved by the compiler.
Examples
  • for $x in 1 to 2 return prof:variables() will dump the values of $x to standard error.

[edit] prof:current-ms

Signatures prof:current-ms() as xs:integer
Summary Returns the number of milliseconds passed since 1970/01/01 UTC. The granularity of the value depends on the underlying operating system and may be larger. For example, many operating systems measure time in units of tens of milliseconds.
Properties In contrast to fn:current-time(), the function is non-deterministic and returns different values every time it is called. Its evaluation order will be preserved by the compiler.
Examples
  • convert:integer-to-dateTime(prof:current-ms()) returns the current miliseconds in the xs:dateTime format.

[edit] prof:current-ns

Signatures prof:current-ns() as xs:integer
Summary Returns the current value of the most precise available system timer in nanoseconds.
Properties In contrast to fn:current-time(), the function is non-deterministic and returns different values every time it is called. Its evaluation order will be preserved by the compiler.
Examples Measures the time of an expression:
let $ns1 := prof:current-ns()
return (
  (: process to measure :)
  (1 to 1000000)[. = 0],
  let $ns2 := prof:current-ns()
  let $ms := ((($ns2 - $ns1) idiv 10000) div 100)
  return $ms || ' ms'
)

[edit] prof:void

Signatures prof:void($value as item()*) as empty-sequence()
Summary Swallows all items of the specified $value and returns an empty sequence. This function is helpful if some code needs to be evaluated and if the actual result is irrelevant.
Properties The function is non-deterministic: evaluation order will be preserved by the compiler.
Examples

[edit] prof:type

Signatures prof:type($expr as item()*) as item()*
Summary Similar to fn:trace($expr, $msg), but instead of a user-defined message, it emits the compile-time type and estimated result size of its argument.

[edit] Changelog

Version 8.5
Version 8.1
Version 7.7
Version 7.6
Version 7.5

This module was introduced with Version 7.3.

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