Working with ENVI Zoom 4.4 and IDL "SEM_CREATE" routine on Mac OS X 10.5 (Leopard)

Topic:
On Mac OS X 10.5 (Leopard) systems, ENVI Zoom 4.4 will not function properly. Additionally, the IDL routine, SEM_CREATE, will not create a semaphore reference. These two issues are related in that the affected ENVI Zoom functionality relies on the IDL SEM_CREATE routine.

This article discusses the errors that might be encountered and an approach that will allow users to work around this problem for ENVI Zoom 4.4 and IDL 6.4.1*.

*Note that IDL 6.4 will not work properly on Mac OS X 10.5. It is recommended that the IDL 6.4.1 patch be applied if using IDL on Mac OS X 10.5. The IDL 6.4.1 patch for Mac OS X 10.5 can be obtained from the following tech tip article: Tech Tip #4284 -- "IDL 6.4.1 update for Mac OS X 10.5"

Discussion:

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SYMPTOMS:

ENVI Zoom

For ENVI Zoom 4.4, operations such as File->Save As... or accessing the Feature Extraction (FX) or RX Anomaly Detection functionality will fail and even crash ENVI Zoom. Error messages encountered may be similar to the following:


• Error
  Failed to create semaphore.
• Warning
  The following error was encountered: SEM_LOCK: Unknown semaphore name provided: MEMSEG_1954281556_SEM. Please consult the supplier of the application.

SEM_CREATE()

The IDL SEM_CREATE() function will unexpectedly return a 0 (error) instead of 1 (success).

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WORKAROUND:

A workaround for these issues follows:

1. Launch IDL 6.4.1 (or ENVI+IDL 4.4) (even in 7-minute demo mode)
   
2. Issue the following command at the IDL (or ENV+IDL) command prompt:
   
   
   PREF_SET, 'IDL_TMPDIR', '/tmp/', /COMMIT

3. Exit IDL (or ENVI+IDL)

Subsequent sessions ENVI Zoom or use of the IDL SEM_CREATE routine should then work as expected.

Note that this workaround should be employed by each user of ENVI Zoom or IDL that encounters these issues on Mac OS X 10.5.



<< Keywords: rxd, envi fx, semaphores >>

Solution:
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