This XQuery Module contains various functions to test and profile code, and to dump information to standard output.
Conventions
All functions and errors in this module are assigned to the http://basex.org/modules/prof
namespace, which is statically bound to the prof
prefix.
Performance Functions
prof:time
Template:Mark $cache
argument removed.
Signatures
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prof:time($expr as item()) as item()*
prof:time($expr as item(), $label as xs:string) as item()*
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Summary
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Measures the time needed to evaluate $expr and outputs a string to standard error or, if the GUI is used, to the Info View. An optional $label may be specified to tag the profiling result. Helpful notes:
- Profiling might change the behavior of your code: An expression that might be executed iteratively will be cached by the profiling function.
- If a value has a compact internal representation, evaluation time will be very low, even if it may take a long time to iterate through all results.
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Properties
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The function is non-deterministic: evaluation order will be preserved by the compiler.
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Examples
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prof:time(prof:sleep(1000)) outputs something similar to 1000.99 ms .
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prof:memory
Template:Mark Renamed (old name: prof:mem
); $cache
argument removed.
Signatures
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prof:memory($expr as item()) as item()*
prof:memory($expr as item(), $label as xs:string) as item()*
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Summary
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Measures the memory allocated by evaluating $expr and outputs a string to standard error or, if the GUI is used, to the Info View. An optional $label may be specified to tag the profiling result. Helpful notes:
- Profiling might change the behavior of your code: An expression that might be executed iteratively will be cached by the profiling function.
- If a value has a compact internal representation, memory consumption will be very low, even if the serialized result may consume much more memory.
- In Java, memory profiling can only be approximative: To improve the measurement, main-memory will be garbage-collected before and after evaluation.
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Properties
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The function is non-deterministic: evaluation order will be preserved by the compiler.
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Examples
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prof:memory((1 to 100000) ! <a/>) will output something similar to 5620 kB .
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prof:track
Template:Mark
Signatures
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prof:track($expr as item()) as item()*
prof:track($expr as item(), $options as map(*)) as item()*
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Summary
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Measures the execution time and memory consumption required for evaluating the specified $expression and returns a map with the results. The following $options are available:
memory : Enables time profiling (default: true).
time : Enables memory profiling (default: true).
value : Returns the value (default: true).
Helpful notes:
- Profiling might change the behavior of your code: An expression that might be executed iteratively will be cached by the profiling function.
- If a value has a compact internal representation, memory consumption will be very low, even if the serialized result may consume much more memory.
- In Java, memory profiling can only be approximative: To improve the measurement, and if the memory option is enabled, main-memory will be garbage-collected before and after evaluation. If you are not interested in the memory consumption, it is advisable to disable this option.
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Properties
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The function is non-deterministic: evaluation order will be preserved by the compiler.
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Examples
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The function call prof:track((1 to 1000000)[. mod 2 = 0]) will return something similar to:
map {
"memory": 41548400,
"time": 34.99,
"value": (2, 4, 6, 8, 10, ...)
}
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prof:current-ms
Signatures
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prof:current-ms() as xs:integer
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Summary
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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.
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Properties
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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.
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Examples
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convert:integer-to-dateTime(prof:current-ms()) returns the current miliseconds in the xs:dateTime format.
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prof:current-ns
Signatures
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prof:current-ns() as xs:integer
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Summary
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Returns the current value of the most precise available system timer in nanoseconds.
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Properties
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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.
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Examples
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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 $ms || ' ms'
)
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Debugging Functions
prof:dump
Signatures
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prof:dump($expr as item()) as empty-sequence()
prof:dump($expr as item(), $label as xs:string) as empty-sequence()
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Summary
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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.
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Properties
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In contrast to fn:trace() , the consumed expression will not be passed on.
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prof:variables
Signatures
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prof:variables() as empty-sequence()
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Summary
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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 .
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Properties
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The function is non-deterministic: evaluation order will be preserved by the compiler.
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Examples
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for $x in 1 to 2 return prof:variables() will dump the values of $x to standard error.
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prof:type
Signatures
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prof:type($expr as item()*) as item()*
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Summary
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Similar to fn:trace($expr, $msg) , but instead of a user-defined message, it emits the compile-time type and estimated result size of its argument.
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Helper Functions
prof:void
Signatures
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prof:void($value as item()*) as empty-sequence()
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Summary
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Swallows all items of the specified $value and returns an empty sequence. This function is helpful if some code needs to be evaluated and if the actual result is irrelevant.
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Properties
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The function is non-deterministic: evaluation order will be preserved by the compiler.
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Examples
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prof:sleep
Signatures
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prof:sleep($ms as xs:integer) as empty-sequence()
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Summary
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Sleeps for the specified number of milliseconds.
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Properties
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The function is non-deterministic: evaluation order will be preserved by the compiler.
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prof:human
Signatures
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prof:human($number as xs:integer) as xs:string
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Summary
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Returns a human-readable representation of the specified $number .
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Example
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prof:human(16384) returns 16K .
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Changelog
- Version 9.0
- Version 8.5
- Version 8.1
- Version 7.7
- Version 7.6
- Version 7.5
This module was introduced with Version 7.3.