#D7CX: I pledge that Devel will have a full Drupal 7 release on the day that Drupal 7 is released.

Note: theme developer module has moved

A suite of modules containing fun for module developers and themers ...

Devel

• Helper functions for Drupal developers and inquisitive admins. This module can print a summary of all database queries for each page request at the bottom of each page. The summary includes how many times each query was executed on a page (shouldn't run same query multiple times), and how long each query took (short is good - use cache for complex queries).
• Also a dprint_r($array) function is provided, which pretty prints arrays. Useful during development. Similarly, a ddebug_backtrace() is offerred.
• much more. See this helpful demo page.

Generate content

Accelerate development of your site or module by quickly generating nodes, comments, terms, users, and more.

Node Access Summary

View the node access entries for the node(s) that are shown on a page. Essential for developers of node access modules and useful for site admins in debugging problems with those modules.

Performance Logging

View and log performance statistics for a site, such as page generation times, and memory usage, for each page load. This is useful for developers and site administrators alike to identify pages that are slow to generate or use excessive memory.

• Settings to enable detailed logging or summary logging. The module defaults to no logging at all.
• Detailed logging causes one database row to be written for each page load of the site. The data includes page generation time in milliseconds, and the number of bytes allocated to PHP, time stamp, ...etc.
• Summary logging logs the average and maximum page generation time, average and maximum memory usage, last access time, and number of accesses for each path.
• Summary is logged to APC, if installed, so as to not cause extra load on the database. This is the only mode recommended for live sites.
• A settings option is available when using summary mode with APC, to exclude pages with less than a certain number of accesses. Useful for large sites.

Compatibility Note:

The Devel module will not work with the old and buggy Zend optimizer 3.2.8 and below (and possibly 3.2.x in general). If you have one of those versions of the Zend optimizer and enable the Devel module it will possibly break your site and may end in a blank screen. If for some reason you still have a problem, see this comment and the rest of that issue.