as the Talend Studio performance decreases drastically with a lot of objects in one job, we are trying to outsource some logic to Subjobs.
Unfortunately there is an error while promoting the context variables back to the main job.
Help would be appreciated.
Maybe you can use a value like -1 or 0 for that context variable which will mean to not use it. You can add a tMap or tFilterRow before your tContextLoad and filter on the value null key/pair. If you do not pass a value, then it is not overwritten. However, the tContextLoad can be configured to ignore, warn or error on these conditions. This way you do not need to deal with null integer values.
Not a great solution, but I personally dislike null Integer values... If possible, which is not always the case, I try to give my numeric variable a value and do not allow nulls.