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Carol Willing
2016-11-11 03:13:51 -08:00
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@@ -168,21 +168,47 @@ If you are interested in building a custom spawner, you can read [this tutorial]
## Spawners, resource limits, and guarantees (Optional) ## Spawners, resource limits, and guarantees (Optional)
Some spawners allow setting CPU and memory limits, or guarantees on the single-user notebook servers. In order to provide a consistent experience for sysadmins and users, we provide a standard way to set and discover memory/cpu limits/guarantees. These must be implemented by the spawner to work. Some spawners of the single-user notebook servers allow setting limits or
guarantees on resources, such as CPU and memory. To provide a consistent
experience for sysadmins and users, we provide a standard way to set and
discover these resource limits and guarantees, such as for memory and CPU. For
the limits and guarantees to be useful, the spawner must implement support for
them.
### Memory Limits & Guarantees ### Memory Limits & Guarantees
In supported spawners, you can set `c.Spawner.mem_limit` to limit the total amount of memory that a single-user notebook server can allocate. Attempting to use more memory than this will cause errors. The single-user notebook server can discover its own memory limit by looking at the environment variable `MEM_LIMIT`, which will be specified in absolute bytes. `c.Spawner.mem_limit`: A **limit** specifies the *maximum amount of memory*
that may be allocated, though there is no promise that the maximum amount will
be available. In supported spawners, you can set `c.Spawner.mem_limit` to
limit the total amount of memory that a single-user notebook server can
allocate. Attempting to use more memory than this limit will cause errors. The
single-user notebook server can discover its own memory limit by looking at
the environment variable `MEM_LIMIT`, which is specified in absolute bytes.
The limit does not claim that you will be able to use all the memory upto your limit. You can set `c.Spawner.mem_guarantee` to to provide a guarantee that at minimum this much memory will always be available for the single-user notebook server to use. The environment variable `MEM_GUARANTEE` will also be set in the single-user notebook server. `c.Spawner.mem_guarantee`: Sometimes, a **guarantee** of a *minumum amount of
memory* is desirable. In this case, you can set `c.Spawner.mem_guarantee` to
to provide a guarantee that at minimum this much memory will always be
available for the single-user notebook server to use. The environment variable
`MEM_GUARANTEE` will also be set in the single-user notebook server.
The underlying system/cluster that the spawner uses is responsible for enforcing these limits and providing these guarantees. If these values are set to `None`, no limits / guarantees are provided, and no environment values are set. The spawner's underlying system or cluster is responsible for enforcing these
limits and providing these guarantees. If these values are set to `None`, no
limits or guarantees are provided, and no environment values are set.
### CPU Limits & Guarantees ### CPU Limits & Guarantees
In supported spawners, you can set `c.Spawner.cpu_limit` to limit the total number of cpu-cores that a single-user notebook server can use. These can be fractional - `0.5` means 50% of one CPU core, `4.0` is 4 cpu-cores, etc. This value is also set in the single-user notebook server's environment variable `CPU_LIMIT`. `c.Spawner.cpu_limit`: In supported spawners, you can set
`c.Spawner.cpu_limit` to limit the total number of cpu-cores that a
single-user notebook server can use. These can be fractional - `0.5` means 50%
of one CPU core, `4.0` is 4 cpu-cores, etc. This value is also set in the
single-user notebook server's environment variable `CPU_LIMIT`. The limit does
not claim that you will be able to use all the CPU up to your limit as other
higher priority applications might be taking up CPU.
The limit does not claim that you will be able to use all the CPU up to your limit - other applications might be taking up CPU. You can set `c.Spawner.cpu_guarantee` to provide a guarantee for CPU usage. The environment variable `CPU_GUARANTEE` will be set in the single-user notebook server when a guarantee is being provided. `c.Spawner.cpu_guarantee`: You can set `c.Spawner.cpu_guarantee` to provide a
guarantee for CPU usage. The environment variable `CPU_GUARANTEE` will be set
in the single-user notebook server when a guarantee is being provided.
The underlying system/cluster that the spawner uses is responsible for enforcing these limits and providing these guarantees. If these values are set to `None`, no limits / guarantees are provided, and no environment values are set. The spawner's underlying system or cluster is responsible for enforcing these
limits and providing these guarantees. If these values are set to `None`, no
limits or guarantees are provided, and no environment values are set.