Why when upgrade gearman python package from 'gearman(2.0.2)' to 'gearman3(0.2.0)', sometimes job missed and delayed

Question

We often used the following code to connect to gearman server to get job:

gm_worker = gearman.GearmanWorker(['localhost:4730'])
gm_worker.set_client_id('xxxworker')
gm_worker.register_task(b'xxx', func1)
gm_worker.work()

With python 2.7.18 and gearman package 'gearman(2.0.2)' installed, the code worked.

As python 2 is runing to the end of lifetime, we upgrade to python 3.6 and installing gearman python package 'gearman3(0.2.0)'. From then on, job sometimes missed, sometimes delayed no more than 10 seconds.

Now we have 2 worker,one for python 2.7.18 and gearman package 'gearman(2.0.2)', still working, but with limited python 2 time span; another for python 3.6 and gearman python package 'gearman3(0.2.0)', job sometimes missing and sometimes delayed.

Till now, we cannot find the cause.

Can somebody help?

Or are there any similar job server like gearman?

                                        Many Thanks!
                                        Howard