3 ms·

I don't know about you, but my application is tested on a single platform/stack with a specific set of operations. When the operation of the thing I'm running o

I don't know about you, but my application is tested on a single platform/stack with a specific set of operations. When the operation of the thing I'm running on changes, my application has changed. It just can't be expected to run the same way. Upgrade means your app is going to work differently. Not only is the app now different, but the upgrade itself is going to be dangerous. The idea that you can just "upgrade a running cluster" is a bit like saying you can "perform maintenance on a rolling car". It is physically possible. It is also a terrible idea. You can do some maintenance while the car is running. Mainly things that are inside the car that don't affect its operation or safety. But if you want to make significant changes, you should probably stop the thing in order to make the change. If you're in the 1994 film Speed and you literally can't stop the vehicle, you do the next best thing: get another bus running alongside the first bus and move people over. Just, uh, be careful of flat tires. (https://www.youtube.com/watch?v=rxQI2vBCDHo https://www.youtube.com/watch?v=rxQI2vBCDHo)

viraptor 8y ago
It really depends on what your scenario/usage is. Sometimes it's a terrible idea: you wouldn't do a live code update on a server handling your blog. Sometimes it's just what you're aiming for: you have expensive hardware plugged into physical lines, there's not enough capacity to migrate data flow uninterrupted, you have to update in place without clients having more than X ms delay. Real life is virtually always the first case... But if you really need it, tech like Java hotswap or elang hot code swap is there.
taeric 8y ago
Picking a dependency for a system that does not have a live method of updating, is a terrible idea for a software system. Physical systems, like a car, have obvious limitations on what can be modified when. Similarly, software will have some limitations on what happens when you are updating. But accepting "upgrades can't be done easily" for software is putting much more limitations on the software than makes sense.
- peterwwillis 8y ago
  With the exception of like, binary patching of executables that use versioned symbols or some craziness like that, virtually all software cannot be upgraded while it is running and expected not to produce errors. I mean, if you use a plug-in style system, you can program it to block operations while a module is reloaded or something. But most software is not designed this way. Especially with ancient monolithic models like Go programs. Upgrades just can't be done easily in a complex system. You can do them without concern for their consequences, but that doesn't mean they're safe or reliable methods.

viraptor 8y ago

It really depends on what your scenario/usage is. Sometimes it's a terrible idea: you wouldn't do a live code update on a server handling your blog. Sometimes it's just what you're aiming for: you have expensive hardware plugged into physical lines, there's not enough capacity to migrate data flow uninterrupted, you have to update in place without clients having more than X ms delay. Real life is virtually always the first case... But if you really need it, tech like Java hotswap or elang hot code swap is there.

taeric 8y ago

Picking a dependency for a system that does not have a live method of updating, is a terrible idea for a software system. Physical systems, like a car, have obvious limitations on what can be modified when. Similarly, software will have some limitations on what happens when you are updating. But accepting "upgrades can't be done easily" for software is putting much more limitations on the software than makes sense.

peterwwillis 8y ago
With the exception of like, binary patching of executables that use versioned symbols or some craziness like that, virtually all software cannot be upgraded while it is running and expected not to produce errors. I mean, if you use a plug-in style system, you can program it to block operations while a module is reloaded or something. But most software is not designed this way. Especially with ancient monolithic models like Go programs. Upgrades just can't be done easily in a complex system. You can do them without concern for their consequences, but that doesn't mean they're safe or reliable methods.