Python agent release notesRSS

Notes

This release of the Python agent includes various improvements and bug fixes related to instrumentation for database client modules, as well as a notable fix to our 'newrelic-admin' script affecting some users who referenced Python virtual environments via a symbolic link.

The agent can be installed using easy_install/pip/distribute via the Python Package Index or can be downloaded directly from our download site.

For a list of known issues with the Python agent see our online help article on the status of the Python agent.

New Features:

• Instrumentation of the WSGI application entry point will now add a new breakdown metric to web transactions corresponding to the finalization of the WSGI request. Within the workings of the interaction between the WSGI server and the WSGI application, this is the point at which the WSGI server will call any close() method on the iterable returned by the WSGI application. The name of this new breakdown metric is 'WSGI/Finalize'. In the case where there was actually a 'close()' method, a further breakdown metric will also appear corresponding to that method.
• Added support to instrumentation for MySQL and PostgreSQL database client modules for monitoring database queries when the database connection object is used as a context manager. Such context manager features are outside of the scope of the Python DBAPI2 (PEP 249) specification, not all database client modules support it and nor do they all work the same. Although supported, we would suggest consideration should be given to not using these context manager features if you need your code to be portable between databases.
• Added support to instrumentation for MySQL database client modules for monitoring database queries when the database connection object was created using the Connect() function. The Connect() function falls outside of the scope of the Python DBAPI2 (PEP 249) specification. Although supported, we would suggest consideration should be given to not using this Connect() function if you need your code to be portable between databases.
• Added database instrumentation support for the mysql-connector-python database client module.
• Custom parameters for a transaction which are a string or numeric value will now be added to and reported with analytic events reported to our analytics system code named Rubicon. This can be disabled using the agent configuration setting 'analytics_events.capture_attributes'.
• The capture of custom parameters against a transaction trace can now be disabled using the agent configuration setting 'transaction_tracer.capture_attributes'.
• The capture of custom parameters against error details can now be disabled using the agent configuration setting 'error_collector.capture_attributes'.

Features Changed:

• The agent API function add_user_attribute() is now deprecated and functionality merged with the add_custom_parameter() function. The latter function should now be used instead. The display of such parameters in browser traces is now optionally enabled with the agent configuration setting 'browser_monitoring.capture_attributes'.

Bug fixes/Improvements:

• If the 'newrelic' package was installed into a Python virtual environment, but the 'newrelic-admin' script was executed via a path that traversed a symlink to the virtual environment, the protections within the agent bootstrapping procedure was detecting that the agent was trying to be used with an application running against a different virtual environment when it was actually the same. This would result in the application not being monitored. This issue was introduced in version 2.8.0 of the agent when additional protections were added against mixing application/modules from different Python virtual environments.
• Explain plans were not being performed on SQL queries made via the executemany() method of a database cursor object. When explain plans are now done, the data inputs from the first row of input data for the executemany() call will be used.
• When using Python 2, if strings were supplied for the web transaction name, custom parameters, in error details etc, and that string contained a series of characters which could not be decoded as valid UTF-8, then an exception would occur. In the case of a web transaction name, this could result in the exception affecting the current web transaction and result in an error response being sent back to a user. For the case of a transaction trace or error details, the exception would prevent the sending of the captured data up to our data collector and it would be discarded. This was a regression within the agent behaviour introduced when Python 3 support was added to the agent.
• Fixed instrumentation for sqlite database modules which could result in instrumentation not being applied correctly, and so no database metrics collected, if the sqlite module had been imported prior to the agent being initialized.
• Limits being applied to the length of the SQL for a slow SQL query when being sent up to our data collector were being applied at the wrong time, resulting in the truncated SQL being used when performing an explain plan. This didn't affect the operation of the web application, but database logs could contain an error about the malformed SQL query.
• Explain plans could be attempted for an SQL query even where the SQL query failed. Under most circumstances a SQL query would fail immediately and so the duration would fall below the threshold for collecting an explain plan, but the changes now made will protect against a long running SQL query which failed in the database and ensure that no additional problem is caused by issuing an explain plan for it.
• If a monitored web application is started up using our newrelic-admin wrapper script, and it executes a separate Python script and that Python script used a Python version older than Python 2.6, the script could output the error message "'import site' failed; use -v for traceback". The execution of the script was not affected, but the message obviously could cause concern.
• The equivalent functions from the 'urllib2' module from Python 2 were not being instrumented when Python 3 was being used. This was missed when Python 3 support was added to the agent.

Notes

This release of the Python agent marks the official introduction of support for pypy. Instrumentation has also been updated to address issues arising from the release of Celery 3.1.

The agent can be installed using easy_install/pip/distribute via the Python Package Index or can be downloaded directly from our download site.

For a list of known issues with the Python agent see our online help article on the status of the Python agent.

New Features:

• The agent has worked with and has already been used by customers with pypy for some time, but we have not officially acknowledged that we support pypy. We have now integrated pypy into our test procedures and now officially support this implementation of the Python language.

Bug fixes/Improvements:

• Instrumentation for Celery has been updated to accommodate changes in Celery 3.1. The changes in Celery 3.1 resulted in no metrics being reported in prior versions of the agent.
• When collecting data on external web service calls, the agent now drops port 80/443 from the name of the host when used with the standard http/https protocol schemes. This ensures that a URL with or without the ports are seen as the same service in the external web services page in the UI.
• When using newrelic.agent.initialize() explicitly, if no arguments are provided, the values for the config file and environment arguments will now be read from the NEW_RELIC_CONFIG_FILE and NEW_RELIC_ENVIRONMENT arguments if specified.
• Flask instrumentation was not correctly mapping URLs related to a HTTP 404 response to a known framework or application handler function. Instead the web transaction was named after the URL, which could result in metric grouping issues if an application was hit with a large number of URLs which couldn't be mapped by the application. Such requests will now be mapped to flask.app:Flask.handle_http_exception.
• Pyramid instrumentation should no longer report as errors instances of exceptions derived from HTTPRedirection, raised to generate a HTTP redirect response.
• Improvements to the newrelic-admin wrapper script and agent bootstrapping procedure to better deal with a local sitecustomize.py file. Changes will also better handle the case where the newrelic-admin wrapper script was used around a Python script using a different Python installation than that which the newrelic package was installed in, avoiding possible errors when the wrapped script was run, due to the mismatch.

Notes

This release of the Python agent contains support for web applications and worker processes using 'gearman' for background task execution. The agent also switches to using the 'json' package from the standard library instead of a separate 'simplejson' package. This should result in potential reductions in base level memory usage by the agent and a reduction of CPU overhead for some environments.

The agent can be installed using easy_install/pip/distribute via the Python Package Index or can be downloaded directly from our download site.

For a list of known issues with the Python agent see our online help article on the status of the Python agent.

New Features:

• Instrumentation now provided for the gearman package. The support covers use of both the gearman client and worker interfaces. In the case of workers, each task executed by the worker will be recorded as a background task and be displayed as such in the New Relic UI.
• The ignore_errors argument to newrelic.agent.record_exception() can now be a callable in addition to being able to pass a sequence. When it is a callable, the callback will be called with the three arguments exc, value and tb, being the same values as returned by sys.exc_info(). The callback should return True if the exception is to be ignored. False if the exception should never be ignored regardless of any other checks, and None if subsequent checks and inbuilt rules should determine if the exception should be ignored. A callback would normally return either True or None.

Bug fixes/Improvements:

• The bundled 'simplejson' package has now been removed and is no longer used. This was previously used due to the requirement to support Python 2.5, for which support was removed in version 2.0.0 of the agent. Instead of simplejson, the 'json' package contained in the Python standard library is now used instead. This should see the base level memory usage of the agent drop as a result. Further, in environments where a C compiler was not available and the C extension modules could not be compiled, there should now be a minimal reduction in the CPU overhead when the agent is uploading data to our backend. This is because the optimised C extension in the json package will always be available as part of the Python standard library and will always be able to be used.
• If a WSGI application was returning an iterable such as a generator, and an exception was raised when a specific part of the response content was yielded from the generator, the details of the exceptions were not being recorded.
• In a multithreaded web application where deferred module imports were being performed in secondary threads, agent registration could fail the first time due to concurrent changes made by the secondary threads to sys.modules. Registration would succeed on a subsequent attempt. This bug was only occurring in Python 2 and was introduced in version 2.0.0 of the agent when Python 3 support was added.
• Custom parameters which were explicitly supplied to newrelic.agent.record_exception() were being ignored and were not appearing in the error details page in the UI. Instead, only custom parameters added using newrelic.agent.add_custom_parameters() against the web transaction or background task itself were being shown. This bug was introduced in version 1.13.0 of the agent when support for cross application tracing was added.
• The port number used in the URL for a web external call, was not being retained when the URL was added as a parameter against the web external node for transaction traces. The port would therefore not be displayed when drilling down into the details of a web external node in a transaction trace.
• The newrelic-admin validate-config command will now work for enterprise high-security mode accounts, provided of course that no setting is otherwise specified in the agent configuration file which is in conflict with that mode. That is, features such as SSL would still need to be enabled by the ssl setting and the capture_params setting indicating whether URL query string parameters should be captured, also set to false.
• When using CherryPy, in addition to the explicit exception type 'NotFound' being ignored as an error, raising of a 'HTTPError' exception where the status is 404 will also be ignored. Similarly, instances of the 'HTTPError' exception will be ignored as an error when they are for a HTTP error in the 30X range.

Notes

This release of the Python agent is a bug fix release primarily to address a number of issues introduced in version 2.2.0.2 which have effected a small number of users.

This version of the agent is also the minimum recommended agent version required to be able to see percentiles and histogram charts. All reporting hosts for an application must be upgraded to the minimum agent version for the feature to be visible.

The agent can be installed using easy_install/pip/distribute via the Python Package Index or can be downloaded directory from our download site.

For a list of known issues with the Python agent see our online help article on the status of the Python agent.

Bug fixes/Improvements:

• Fixed issues with instrumentation wrappers which caused failure of WSGI application integration for FASTCGI/SCGI/AJP using flup.
• Fixed issues with instrumentation wrappers which caused failure of wrappers for external web service calls in certain uses cases.
• Fixes issues with instrumentation wrappers which caused failure when queuing Celery tasks from within a web application using django-celery.
• When using the ErrorTrace context manager to capture details of exceptions within a certain context, None can now be passed for the transaction and an assertion failure will not be raised. This avoids the need to check explicitly to see if a web request is being monitored and avoid using ErrorTrace where there isn't.

Notes

This release of the Python agent is a hot fix version to address a Celery instrumentation issue introduced with version 2.2.0.2.

The agent can be installed using easy_install/pip/distribute via the Python Package Index or can be downloaded directory from our download site.

For a list of known issues with the Python agent see our online help article on the status of the Python agent.

Bug fixes/Improvements:

• Fixed bug with Celery instrumentation introduced with version 2.2.0.2 of the agent. The bug was causing a Python exception to be raised when the instrumentation was trying to derive the task name to use as the name of the background task.

Notes

This release of the Python agent is an incremental release and includes minor feature changes and enhancements.

The agent can be installed using easy_install/pip/distribute via the Python Package Index or can be downloaded directory from our download site.

For a list of known issues with the Python agent see our online help article on the status of the Python agent.

New Features:

• Use of HTTP proxies over SSL using the HTTP CONNECT tunnelling mechanism is now supported. Set the 'proxy_scheme' to 'http' to invoke this mode. This will become the default in a future version of the agent. If migrating from an older agent version and need to keep the existing behaviour going forward, set 'proxy_scheme' to 'https'. Alternatively, ensure you provide the scheme in the form of a URI as part of the 'proxy_host' setting.
• Added request queueing support to the instrumentation for the Tornado ASYNC framework. Request queueing times should start showing in the APM Overview page when a frontend web server such as Nginx, has been configured to add the appropriate headers. For more details see our documentation on setting up tracking of queueing time.
• The 'newrelic.agent.record_exception()' can now be called without actually passing it any exception details. In this case, the details of any current exception being handled will be used instead.
• Added a new mechanism for automatic discovery of third party instrumentation modules as an alternative to having to list them explicitly in the agent configuration file. Any such instrumentation module should register entry points under the 'newrelic.hooks' group in 'setup.py' for that package. The entries should be of the form 'target-module = instrumentation-module:function'. When the 'target-module' is imported, the function 'instrumentation-module:function' will be executed and passed the module. Any instrumentation module should then use functions provided by our agent API under 'newrelic.agent' to instrument the module as necessary.

Bug fixes/Improvements:

• When using the CherryPy web framework, the NotFound, InternalRedirect and HTTPRedirect exceptions if raised are now ignored and not treated as errors.
• When using the Pyramid web framework, if a view could not be found to handle a request, it could cause the agents' Pyramid instrumentation to fail, causing an exception.
• When using the Pyramid web framework, the PredicateMismatch exception if raised when trying to resolve a URL to a view handler is now ignored and not treated as an error.
• Updated the instrumentation for the pywapi module to drop support for the now discontinued Google weather API.
• Overhauled the mechanisms used to wrap instrumentation around functions to be monitored. When the agent is installed, if the optional C extension module can be compiled and installed, then the new wrappers should have a reduced overhead compared to the pure Python versions of the wrappers otherwise used.
• Running thread profiles on coroutine (gevent/eventlet) based systems no longer cause a timeout in the UI. Although the UI now no longer times out, as explained in our status of the Python agent documentation, we still however do not generate any results when running thread profiling on coroutine based systems.

Notes

This release of the Python agent is a major new version and primarily focuses on the addition of support for Python 3.

The agent can be installed using easy_install/pip/distribute via the Python Package Index or can be downloaded directory from our download site.

For a list of known issues with the Python agent see our online help article on the status of the Python agent.

New Features:

• Python 3.3 or later is now supported. This includes support for popular web frameworks that have been ported to Python 3, such as CherryPy, Django, Flask, Pyramid and Tornado.
• Added new instrumentation to track as external service calls, requests made by the 'thrift' client module.
• Added new instrumentation to track memcache calls made by the 'bmemcached' client module.

Features Removed:

• Python 2.5 is no longer supported. The minimum required Python version is now 2.6. If using Python 2.5, you should ensure that any requirement for the 'newrelic' module listed in a 'setup.py' or pip requirements file says 'newrelic<2.0.0.0'.

Bug fixes/Improvements:

• Fixed broken instrumentation for 'httplib' module, which would cause an exception where the 'httplib' connect() method was being invoked via the Connection class type rather than an instance of the Connection class.
• Fixed issue where if the host system clock was wound backwards, then the response time of active requests could be set as being zero, resulting in a ZeroDivisionError when calculating thread utilization.
• Fixed issue where the use of SSL via a HTTP proxy by the agent to connect to the New Relic data collector to report data would fail.
• Fixed broken instrumentation for sqlite database client module which resulted in the executescript() API call failing.
• Add workaround for uWSGI issue where when using gevent mode of uWSGI, it would attempt to wait on all greenlets on process shutdown, instead of only on non daemon threads, specifically the request threads. The issue was causing processes to hang for 60 seconds on shutdown before the uWSGI master process killed the process. We are in discussion with uWSGI authors about a permanent fix to uWSGI.

Notes

This release of the Python agent includes a hot fix to address an issue whereby external web service calls made via HTTPS connections were failing. This issue was introduced with version 1.13.0.30 of the agent.

The agent can be installed using easy_install/pip/distribute via the Python Package Index or can be downloaded directory from our download site.

For a list of known issues with the Python agent see our online help article on the status of the Python agent.

Bug fixes/Improvements:

• The Cross Application Tracing feature added in version 1.13.0.30 of the agent was causing failure of external web service calls made over HTTPS connections when that call was made via the 'httplib' module. As the 'httplib' module is used internally in other HTTP client libraries such as the 'urllib', 'urllib2', 'urllib3' and 'requests' modules, they would also have been affected.
• Setting the 'cross_application_tracer.enabled' setting in the agent configuration file to 'false' to disable Cross Application Tracing would cause an exception when an external web service call was being made via the 'httplib' module.

Notes

This release of the Python agent adds support for Cross Application Tracing.

The agent can be installed using easy_install/pip/distribute via the Python Package Index or can be downloaded directory from our download site.

For a list of known issues with the Python agent see our online help article on the status of the Python agent.

New features:

• Support for New Relic's Cross Application Tracing feature is now available for the Python agent. This feature enables correlation of transaction traces between different services in your stack. It works on external calls made between applications monitored by any New Relic agents (Java, .NET, Ruby and Python), which support this feature. At this time the Python agent supports this feature on outgoing calls when using the 'httplib' module or any other module which uses 'httplib', such as the 'urllib', 'urllib2', 'urllib3' and 'requests' modules. Any inbound calls from other agents which support the feature will also be handled.
• Added instrumentation for the weberror package. This provides visibility into potentially blocking operations such as sending of email for exceptions which are being reported.
• Added instrumentation for the umemcache package.
• Added instrumentation for the DBAPI2 compliant interface for the IBM DB2 ibm_db_dbi database client package.

Bug fixes/Improvements:

• When running a WSGI application under the Tornado WSGI container, data reporting would stop if an unhandled exception managed to propagate back up to the Tornado WSGI container. This was due to a bug in Tornado in respect of its compliance with the WSGI specification. A workaround is provided to avoid the problems this caused to the Python agent. Tornado versions prior to 3.2 will still carry that bug however and we make no attempt to address the bug in Tornado.
• The Tornado instrumentation was causing template rendering to fail where a relative path was used to refer to the template and no template path had been specified for the RequestHandler instance or globally.
• The Tornado instrumentation was causing exceptions when using the @tornado.gen decorators under Tornado 2.X.
• When using Django, web transactions will now be named after individual view handlers when using class based views, rather than being named after the class itself.
• When using Pyramid, web transactions will now be named after individual view handlers when using view classes, rather than being named after the class itself.
• Celery instrumentation had stopped working correctly for Celery versions 2.5.3 through 2.5.5.
• No data was being reported where a monitored process was being shutdown within a couple of seconds of being started even if the agent was able to register. This could result in custom metrics in particular not being reported.
• SSL certificate validation was failing on older Debian systems due to the OpenSSL libraries not being able to process a couple of the certificates bundled with the Python agent. Those certificates were not required and have been removed.
• Calculation of a time string was failing on Windows due to using a strftime() formatter which only existed on UNIX systems.