enitre "produce" block executes twice?

[mqualls]

I was using a FileTreeBuilder to set up some configuration files and kept finding the contents of the file were repeated. It turns out, the produce block it was in was running twice. This seems to happen to any produce block, such as in this minimal example:

test = {

       produce("a") {

               println "doing a"

               exec("echo a > a")

       }

}

Bpipe.run {

       test

}

"doing a" will print twice
This is using 0.9.9.6

[Simon Sadedin]

Hi,

Indeed it can get executed twice.

This could probably be made clearer in the documentation: in order to discover what outputs and inputs will be produced by the body of the produce statement, Bpipe will execute it in a mode where none of the "exec" statements do anything. So the exec will only happen once, but the code inside the produce block itself can execute twice. For this reason it's important that such code either be robust to that ("idempotent" in a sense - doing it twice is the same as doing it once).

Cheers,

Simon

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