The last I worked with was Morpheus.
...so?
The pooled memory allocation self-corrected common memory leak issues.
There is no 'pooled memory allocation' of a VM. A VM does not 'self correct' anything.
Since allocation is virtual and not physical, failure to release memory is addressed at the hypervisor level.
Allocation of memory for a VM is physical memory. How the VM handles that memory is up to the VM.
False equivalence.
This won't correct 100% of memory leak issues, but will correct a good 90%.
Argument from randU fallacy. Memory is not 'corrected' by a VM. Any process running in a VM can leak memory just like a base process can.
Lockheed ran MasterCam - the king of memory leaks and Morpheus managed pooling well enough that nightly reboots were no longer needed on the engineering servers as they were with physical boxes.
Any VM process can leak memory just like a base process can. Rebooting a VM is just as necessary as rebooting a machine.
But the most common issue that required a reboot was network related, NIC chatter, 16X bonding of gigabit cards could often end up in collision storms with the switch, especially is someone did what they loved to do in El Segundo and tossed in a SOHO unmanaged, the little blue Linksys rodents that would infest departments.
Linksys is not a rodent.
VMs do not have hard NICs.
There is no such thing as a 'collision storm with a switch'.
Further, enterprise level hypervisors,
There is no such thing as an 'enterprise level hypervisor'.
VMWare ESXi or HP Morpheus are clustered. If a host is acting up, fail over rather than incur downtime.
Failover means abandoning one of the VMs because it crashed. Usually the VM is automatically rebooted and returns to the pool upon recovery.
Cloud farms use massive scale clustering to maximize uptime.
'scale clustering' is a buzzword.
Servers for cloud services (including such cloud services as AWS, Azure, and Google) are built to scale, yes.
They are also built to 'cluster', or have established pools of VMs they can turn to as needed to run tasks in parallel, and to cover failure of a VM.
The need to reboot a VM based server should be as rare as seeing bigfoot.
A VM still suffers all the problems a base machine does. They are rebooted all the time due to memory leaks, crashed process detection, or simply adding to the cluster pool.
It sounds like you are believing the marketing hype but not the actual method of how this stuff is implemented.
It is the holographic nature of the way VMs are allocated to conduct cloud services that makes them so reliable and scalable. An individual VM can crash, and it doesn't really affect the cloud service at all. Whole server farms can physically be destroyed and the service keeps on running in another server farm.
VMs can be programmed to automatically reboot when they crash, essentially emulating the 'power restored' feature of a BIOS.