Sloeber blocks Uploads

[PeterSued]

I like Sloeber (and Eclipse) much more than Arduino-IDE, but...
Pretty often I have the situation, that starting Build or Upload is not possible because Sloeber/Eclipse is busy updating or 'finishing the installation'. Error message:
Please wait for the 'arduino installer job' to finish. Look at right bottom of the eclipse window to see if it is still running.

• This job never ends
• Cancelling it either has no effect at all, or takes very long until the process finally stops

I have read that long path-names might be a problem, so I reduced my path to Sloeber to: "D:\Tools\Sloeber" - this did not help.

[jantje]

See #1731 for problem description and workarounds