tx-parallex

parallex

System Requirements

Python >= 3.8

install

Default object store

pip install tx-parallex

Plasma store https://arrow.apache.org/

pip install tx-parallex[arrow]

Install from source

• Clone the repo
• Easy install instructions:

# Create a virtual environment called 'px'
conda create -n px python=3.8
# start-up the environment you just created
conda activate px
# install the rest of the tx-parallex pre-requirements
pip install -r requirements.txt

• Test

# run the tests, a number of test 'specs'
PYTHONPATH=src pytest -x -vv --full-trace -s --timeout 60
# deactivate the environment (if desired)
conda deactivate

set log level

set environment variable LOG_LEVEL to one of Python's logging library setLevel.

Introduction

A queue with dependencies

Usage

from tx.parallex import run_python

ret = run_python(number_of_workers = 4, pyf = "spec.py", dataf = "data.yml")

Spec

tx-parallex specs can be written in YAML or a Python-like DSL. The Python-like DSL is translated to YAML by tx-parallex. Each object in a spec specifies a task. When the task is executed, it is given a dict called data. The pipeline will return a dictionary.

YAML

Assuming you have a function sqr defined in module math which returns the square of its argument.

def sqr(x):
  return x * x

let

The let task sets data for its subtask. It adds a new var value pair into data within the scope of its subtask, and executes that task.

Syntax:

type: let
var: <var>
obj: <value>
sub: <subtask>

Example:

type: let
var: a
obj:
  data: 1
sub:
  type: python
  name: y
  mod: math
  func: sqr
  params: 
    x:
      name: a

map

The map task reads a list coll from data and applies a subtask to each member of the list. The members will be assigned to var in data passed to those tasks

Syntax:

type: map
coll: <value>
var: <variable name>
sub: <subtask>

<value> is an object of the form:

Reference an entry in data or the name of a task

"name": <variable name>

Constant

"data": <constant>

Example:

type: map
coll: 
  data:
  - 1
  - 2
  - 3
var: a
sub:
  type: python
  name: y
  mod: math
  func: sqr
  params: 
    x:
      name: a

cond

The cond task reads a boolean value and if it is true then it executes the then task otherwise it executes the else task.

Syntax:

type: cond
on: <value>
then: <subtask>
else: <subtask>

Example:

type: cond
on: 
  data:
    true
then:
  type: ret
  obj:
    data: 1
else:
  type: ret
  obj:
    data: 0

python

You can use any Python module.

The python task runs a Python function. It reads parameters from data. The return value must be pickleable.

Syntax:

type: python
name: <name>
mod: <module>
func: <function>
params: <parameters>

<parameters> is an object of the form:

<param> : <value>
...
<param> : <value>

where <param> can be either name or position.

Example:

  type: python
  name: y
  mod: math
  func: sqr
  params: 
    x:
      data: 1

top

The top task toplogically sorts subtasks based on their dependencies and ensure the tasks are executed in parallel in the order compatible with those dependencies.

Syntax:

type: top
sub: <subtasks>

It reads the name properties of subtasks that are not in data.

Example:

type: top
sub:
- type: python
  name: y
  mod: math
  func: sqr
  params: 
    x:
      data: 1
- type: python
  name: z
  mod: math
  func: sqr
  params: 
    x:
      name: y

seq

The seq task forces all subtasks to be run sequentially.

Syntax:

type: top
sub: <subtasks>

It reads the name properties of subtasks that are not in data.

Example:

type: seq
sub:
- type: python
  name: y
  mod: math
  func: sqr
  params: 
    x:
      data: 1
- type: python
  name: z
  mod: math
  func: sqr
  params: 
    x:
      name: y

ret

ret specify a value. The pipeline will return a dictionary. When a task appears under a map task, it is prefix with the index of the element in that collection as following

<index>

For nested maps, the indices will be chained together as followings

<index>. ... .<index>

Syntax:

type: ret
obj: <value>

Example:

type: ret
obj: 
    name: z

Python

A dsl block contains a subset of Python.

• There is a semantic difference from python. Any assignment in block is not visiable outside of the block.
• Assignment within a block are unordered
• return statement

Available syntax:

import

from <module> import *
from <module> import <func>, ..., <func>

import names from module

<module> absolute module names

assignment

<var> = <const>

where

<const> = <integer> | <number> | <boolean> | <string> | <list> | <dict>

This translates to let.

Example:

a = 1
y = sqr(x=a)
yield y

function application

<var> = [<module>.]<func>(<param>=<expr>, ...) | <expr>

This translate to python. where <var> is name <expr> is

<expr> = <expr> if <expr> else <expr> | <expr> <binop> <expr> | <expr> <boolop> <expr> | <expr> <compare> <expr> | <unaryop> <expr> | <var> | <const>

<binop>, <boolop> and <compare> and <unaryop> are python BinOp, BoolOp, Compare, and UnaryOp. <expr> is translated to a set of assignments, name, or data depending on its content.

Example:

y = math.sqr(1)
z = math.sqr(y)
return z

parallel for

for <var> in <expr>:
    ...

This translates to map.

Example:

for a in [1, 2, 3]:
  y = math.sqr(a)
  yield y

if

if <expr>:
    ...
else:
    ...

This translates to cond.

Example:

if z:
    yield 1
else:
    yield 0

The semantics of if is different from python, variables inside if is not visible outside

with

with Seq:
    ...

This translates to seq.

Example:

with Seq:
    y = math.sqr(1)
    return y

yield

yield <expr>

This translates to ret.

Example:

y = math.sqr(1)
return y

Data

data can be arbitrary yaml