Github user paul-rogers commented on a diff in the pull request: https://github.com/apache/drill/pull/868#discussion_r130187202 --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/server/options/TypeValidators.java --- @@ -217,19 +236,52 @@ public void validate(final OptionValue v, final OptionSet manager) { } } + /** Max width is a special validator which computes and validates + * the maxwidth. If the maxwidth is already set in system/session + * the value is returned or else it is computed dynamically based on + * the available number of processors and cpu load average + */ + public static class MaxWidthValidator extends TypeValidator{ + + public MaxWidthValidator(String name) { + this(name, false); + } + + public MaxWidthValidator(String name, boolean isAdminOption) { + super(name, Kind.LONG, isAdminOption); + } + + public void loadDefault(DrillConfig bootConfig) { + OptionValue value = OptionValue.createLong(OptionType.SYSTEM, getOptionName(), bootConfig.getLong(getConfigProperty()), OptionScope.BOOT); + setDefaultValue(value); + } + + public int computeMaxWidth(double cpuLoadAverage, long maxWidth) { + // if maxwidth is already set return it + if (maxWidth != 0) { + return (int) maxWidth; + } + // else compute the value and return + else { + int maxWidthPerNode; + int availProc = Runtime.getRuntime().availableProcessors(); + maxWidthPerNode = (int) Math.max(1, Math.min(availProc, Math.round(availProc * cpuLoadAverage))); --- End diff -- `int maxWidthPerNode = ...` or even just `return (int) ...`
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