PerilousApricot opened a new pull request #34903:
URL: https://github.com/apache/spark/pull/34903
When loading config defaults via spark-env.sh, it can be useful to know
the current pyspark python interpreter to allow the configuration to set
values properly. Pass this value in the environment as
_PYSPARK_DRIVER_SYS_EXECUTABLE to the environment script.
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### What changes were proposed in this pull request?
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It's currently possible to set sensible site-wide spark configuration
defaults by using `$SPARK_CONF_DIR/spark-env.sh`. In the case where a user is
using pyspark, however, there are a number of things that aren't discoverable
by that script, due to the way that it's called. There is a chain of calls
(java_gateway.py -> shell script -> java -> shell script) that ends up
obliterating any bit of the python context.
This change proposes to add en environment variable
`_PYSPARK_DRIVER_SYS_EXECUTABLE` which points to the filename of the top-level
python executable within pyspark's `java_gateway.py` bootstrapping process.
With that, spark-env.sh will be able to infer enough information about the
python environment to set the appropriate configuration variables.
### Why are the changes needed?
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Right now, there a number of config options useful to pyspark that can't be
reliably set by `spark-env.sh` because it is unaware of the python context that
spawning the executor. To give the most trivial example, it is currently
possible to set `spark.kubernetes.container.image` or `spark.driver.host` based
on information readily available from the environment (e.g. the k8s downward
API). However, `spark.pyspark.python` and family cannot be set because when
`spark-env.sh` executes it's lost all of the python context. We can instruct
users to add the appropriate config variables, but this form of cargo-culting
is error-prone and not scalable. It would be much better to expose important
python variables so that pyspark can not be a second-class citizen.
### Does this PR introduce _any_ user-facing change?
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Yes. With this change, if python spawns the JVM, `spark-env.sh` will receive
an environment variable `_PYSPARK_DRIVER_SYS_EXECUTABLE` pointing to the python
executor.
### How was this patch tested?
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To be perfectly honest, I don't know where this fits into the testing
infrastructure. I monkey-patched a binary 3.2.0 install to add the lines to
java_gateway.py and that works, but in terms of adding this to the CI ... I'm
at a loss. I'm more than willing to add the additional info, if needed.
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