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[LDM #UXH-476510]: using ldmsend problem

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  • Subject: [LDM #UXH-476510]: using ldmsend problem
  • Date: Fri, 03 Sep 2010 10:07:38 -0600
Robin,

> Full Name: robin wang
> Email Address: address@hidden
> Organization: center weather breau
> Package Version: 6.8.1
> Operating System: linux ES 5.5
> Hardware: HPDX7200 , intel 2.8G cpu, 2G memory, 160G HD
> Description of problem: we encounter some problem about using ldmsend
> 1. Is there a minimum file size limit for ldmsend utility ? (file size can be 
> zeor ?)

Whether or not the ldmsend(1) utility can send a zero-length file depends on 
the return value of the system-call "malloc(0)".  If it returns a non-NULL 
pointer (as most systems do), then the zero-length file can be sent. If, 
however, it returns NULL, then ldmsend(1) will print an error message and 
continue with the next file to be sent.

Are you seeing the error message "Couldn't allocate 0 bytes for product data"? 
If so, then your ldmsend(1) can't send a zero-length file; otherwise, it can.

I'll see about fixing ldmsend(1) so that it can send a zero-length file 
regardless of how "malloc(0)" behaves. Thanks for asking this question.

> 2. If we send a certain file more than 2 times, ldmsend  seem to don't send 
> it again ? How to send the same file again ? It has a timeout period ?

Because the signature (i.e., MD5 checksum) of the data of all zero-length files 
is the same, the receiving LDM will reject the zero-length data-product if its 
product-queue already contains a zero-length data-product.  One solution would 
be to send a file that contains a timestamp rather than nothing.  If the 
timestamps have sufficient resolution, then their signatures will differ and 
they will not be rejected as duplicates.

> 3. how to send notify (a token,or  a file  with   null file size) ?
> 
> Very Thanks for your assist

Regards,
Steve Emmerson

Ticket Details
===================
Ticket ID: UXH-476510
Department: Support LDM
Priority: Normal
Status: Closed