PHP Research & Evidence-Based Practice 2 — Questions and Answers
Question 1: Which PHP function returns the execution time in microseconds and is commonly used in performance benchmarking research?
- time()
- microtime(true) (Correct answer)
- hrtime(true)
- clock_gettime()
Correct answer: microtime(true)
microtime(true) returns the current Unix timestamp as a float including microseconds, making it useful for measuring script execution time.
Question 2: When profiling a PHP application to identify bottlenecks, which tool is specifically designed for PHP and integrates with IDEs like PhpStorm?
- Blackfire
- Xdebug (Correct answer)
- New Relic
- Tideways
Correct answer: Xdebug
Xdebug is a PHP extension that provides debugging and profiling capabilities and integrates directly with IDEs like PhpStorm.
Question 3: Which PHP testing framework method is used to assert that two values are identical (type and value) rather than merely equal?
- assertEquals()
- assertSame() (Correct answer)
- assertIdentical()
- assertStrict()
Correct answer: assertSame()
assertSame() in PHPUnit checks both value and type equality using === comparison, unlike assertEquals() which uses ==.
Question 4: In evidence-based PHP development, what does the term 'code coverage' specifically measure?
- Lines of code written per developer
- Percentage of source code executed during tests (Correct answer)
- Number of bugs found per release
- Documentation completeness ratio
Correct answer: Percentage of source code executed during tests
Code coverage measures the percentage of source code lines, branches, or paths that are executed when the test suite runs.
Question 5: Which PHP function can be used to log script errors to a custom file for later analysis?
- debug_log()
- error_log() (Correct answer)
- log_error()
- write_log()
Correct answer: error_log()
error_log() sends an error message to PHP's error log, a file, or a remote host, depending on the message_type parameter.
Question 6: When conducting A/B testing in a PHP web application, which header manipulation approach helps ensure consistent user segmentation?
- Using PHP sessions to store the test group assignment (Correct answer)
- Rotating DNS between servers
- Changing the HTTP method per request
- Using different PHP versions per user
Correct answer: Using PHP sessions to store the test group assignment
PHP sessions persist across requests and ensure the same user consistently receives the same variant throughout the experiment.
Question 7: Which PHP extension provides detailed memory usage statistics useful for diagnosing memory leaks in long-running scripts?
- memory_get_peak_usage()
- Xdebug memory profiler (Correct answer)
- Valgrind PHP binding
- APCu stats
Correct answer: Xdebug memory profiler
Xdebug's memory profiler generates detailed call-by-call memory usage data that can identify leaks in long-running PHP processes.
PHP Research & Evidence-Based Practice 2
Which PHP function returns the execution time in microseconds and is commonly used in performance benchmarking research?