S390x jobs are stuck in the received state for days

As you can see at https://travis-ci.com/github/apache/arrow/builds, more than 10 jobs are queued from the last Friday.
Most of the jobs have not almost executed. A job might be processed very slowly (two or three days after submitted).

Would it be possible to look at and fix this issue?

I realized that travisCi jobs on s390x for other repositories works well (no delay). The delay problem for the starting job seems to be only on arrow repository.
Is there any way to resolve this issue?

In this case, this looks like

Thank you for your reply. This happened one month ago. Did Oracle have a lot of jobs in the queue again?

I also see that you’re building on travis-ci.org, so this also looks like