Libraries and Applications do not account for the Leap Second

Environment

• Red Hat Enterprise Linux 4
• Red Hat Enterprise Linux 5
• Red Hat Enterprise Linux 6
• Red Hat Enterprise Linux 7

Issue

• Libraries, such as python and other code bases, and third party applications do not account for the leap second.

Resolution

• This issue must be addressed on a case by case basis depending on library or application in use. For example, in an application that calculates time deltas ensure that a negative value is considered for cases where the leap second be inserted. In the event that there is an error the application vendor responsible should be contacted to address these, as Red Hat has no control over third party applications.

Workarounds: Note that each application may have specific workarounds outside of the ones below; however, these will need to be discussed with the application vendor. The following list should prevent many issues in third party applications:

1. Run ntp in slew mode during the leap second, as documented in What does "ntpd -x" mean? Can I run NTP in slewmode?.
2. Disable ntp the day prior to the leap second and wait for the event to have passed. After this point shut down the application, restart ntp, and then restart the application after the leap second has been inserted. This is not recommended as system time will not be synchronized

Root Cause

• The leap second was not considered when performing time calculations.

Diagnostic Steps

• The following traceback is seen in python applications:

Traceback (most recent call last): File "<stdin>", line 1, in <module> ValueError: second must be in 0..59

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