No support for multiple fluentd workers

Hi,

I need to use multiple fluentd workers, and when trying to do that looks like mdsd plugin doesn't support multiple workers.

fluentd conf:
```

workers 4



@type forward
port 24224
bind 0.0.0.0


@type prometheus

name fluentd_input_status_num_records_total
type counter
desc The total number of incoming records

tag ${tag}
hostname ${hostname}





@type record_modifier

# NOTE: This Ruby code written in ${} has to be written in one line!
_temp_ ${ if record.has_key?("log"); begin; parsed = JSON.parse(record["log"]); parsed.each do |key, value|; record[key] = value; end; rescue; record["message"] = record["log"]; end; end; nil }
_ine_ ${ if record.has_key?("LOG"); begin; record["LOG"].each do |key, value|; record[key] = value; end; rescue; record["message"] = record["LOG"]; end; end; nil }
_kube_ ${ if record.has_key?("kubernetes"); begin; kube = record["kubernetes"]; kube.each do |key, value|; record[key] = value; end; rescue; end; end; nil}
_build_id_ ${ begin; record["build_id"] = record["container_image"].split(':')[1].split('-')[0] if record.has_key?("container_image"); rescue; end; nil}
_service_ ${ if record.has_key?("labels"); record["service_name"] = record["labels"]["app_kubernetes_io/name"] if record["labels"].has_key?("app_kubernetes_io/name") end; nil;}
_node_ ${ record["node"] = record["host"] if record.has_key?('host'); nil}

remove_keys _temp_, _kube_, _service_, _build_id_, _node_, host, log, namespace_id, pod_id, container_image, container_image_id, namespace_labels, master_url, docker, kubernetes, _ine_



@type rewrite_tag_filter

key SOURCE
pattern ^(OmsTelemetryLog)$
tag custom.$1


key SOURCE
pattern ^(OmsTelemetryLog)$
tag custom.${tag}
invert true




@type record_modifier
remove_keys DATA, TAG, SOURCE, stream, kubernetes, source1, LOG



@type copy

@type mdsd
@log_level info
# Full path to mdsd dynamic json socket file
djsonsocket /var/run/mdsd/default_djson.socket
# Max time in milliseconds to wait for mdsd acknowledge response. If 0, no wait.
acktimeoutms 5000
# An array of regex patterns for mdsd source name unification purpose.
# The passed will be matched against each regex, and if there's a match, the matched substring will be used as the resulting mdsd source name.
mdsd_tag_regex_patterns ["kubernetes", "OmsTelemetryLog"]
# Convert hash value to valid json.
convert_hash_to_json true

@type file
path /var/log/td-agent/buffer/kubernetes_out_mdsd.buffer
chunk_limit_size 8m
queued_chunks_limit_size 2048
flush_interval 15s
flush_thread_count 1
flush_at_shutdown true
retry_max_times 10
retry_timeout 10m



@type prometheus

name fluentd_output_status_num_records_total
type counter
desc The total number of outgoing records

tag ${tag}
hostname ${hostname}

```

When starting fluentd I get this (before it's crashed):
```
2020-07-10 07:45:18 +0000 [info]: starting fluentd-1.9.2 pid=7 ruby="2.4.9"
2020-07-10 07:45:18 +0000 [info]: spawn command to main: cmdline=["/opt/td-agent/embedded/bin/ruby", "-Eascii-8bit:ascii-8bit", "/opt/td-agent/embedded/bin/fluentd", "-c", "/etc/fluentd/fluentd.conf", "--log", "/dev/stdout", "--under-supervisor"]
2020-07-10 07:45:18 +0000 [info]: adding filter pattern="kubernetes.**" type="prometheus"
2020-07-10 07:45:19 +0000 [info]: adding filter pattern="kubernetes.**" type="record_modifier"
2020-07-10 07:45:19 +0000 [info]: #1 adding rewrite_tag_filter rule: SOURCE [#, /^(OmsTelemetryLog)$/, "", "custom.$1"]
2020-07-10 07:45:19 +0000 [info]: #1 adding rewrite_tag_filter rule: SOURCE [#, /^(OmsTelemetryLog)$/, "!", "custom.${tag}"]
2020-07-10 07:45:19 +0000 [info]: adding match pattern="kubernetes.**" type="rewrite_tag_filter"
2020-07-10 07:45:19 +0000 [info]: #0 adding rewrite_tag_filter rule: SOURCE [#, /^(OmsTelemetryLog)$/, "", "custom.$1"]
2020-07-10 07:45:19 +0000 [info]: #0 adding rewrite_tag_filter rule: SOURCE [#, /^(OmsTelemetryLog)$/, "!", "custom.${tag}"]
2020-07-10 07:45:19 +0000 [info]: adding filter pattern="custom.**" type="record_modifier"
2020-07-10 07:45:19 +0000 [error]: #1 config error file="/etc/fluentd/fluentd.conf" error_class=Fluent::ConfigError error="Plugin 'mdsd' does not support multi workers configuration (Fluent::OutputMdsd)"
2020-07-10 07:45:19 +0000 [error]: fluent/log.rb:362:error: config error file="/etc/fluentd/fluentd.conf" error_class=Fluent::ConfigError error="Plugin 'mdsd' does not support multi workers configuration (Fluent::OutputMdsd)"
2020-07-10 07:45:19 +0000 [info]: adding match pattern="custom.**" type="copy"
2020-07-10 07:45:19 +0000 [info]: Worker 1 finished unexpectedly with status 2
2020-07-10 07:45:19 +0000 [info]: Received graceful stop
2020-07-10 07:45:19 +0000 [info]: #3 adding rewrite_tag_filter rule: SOURCE [#, /^(OmsTelemetryLog)$/, "", "custom.$1"]
2020-07-10 07:45:19 +0000 [info]: #3 adding rewrite_tag_filter rule: SOURCE [#, /^(OmsTelemetryLog)$/, "!", "custom.${tag}"]
2020-07-10 07:45:19 +0000 [error]: #0 config error file="/etc/fluentd/fluentd.conf" error_class=Fluent::ConfigError error="Plugin 'mdsd' does not support multi workers configuration (Fluent::OutputMdsd)"
2020-07-10 07:45:19 +0000 [error]: fluent/log.rb:362:error: config error file="/etc/fluentd/fluentd.conf" error_class=Fluent::ConfigError error="Plugin 'mdsd' does not support multi workers configuration (Fluent::OutputMdsd)"
2020-07-10 07:45:19 +0000 [info]: Worker 0 finished with status 2
2020-07-10 07:45:19 +0000 [info]: Received graceful stop
2020-07-10 07:45:19 +0000 [info]: Received graceful stop
2020-07-10 07:45:19 +0000 [info]: #2 adding rewrite_tag_filter rule: SOURCE [#, /^(OmsTelemetryLog)$/, "", "custom.$1"]
2020-07-10 07:45:19 +0000 [info]: #2 adding rewrite_tag_filter rule: SOURCE [#, /^(OmsTelemetryLog)$/, "!", "custom.${tag}"]
2020-07-10 07:45:19 +0000 [error]: #3 config error file="/etc/fluentd/fluentd.conf" error_class=Fluent::ConfigError error="Plugin 'mdsd' does not support multi workers configuration (Fluent::OutputMdsd)"
2020-07-10 07:45:19 +0000 [error]: fluent/log.rb:362:error: config error file="/etc/fluentd/fluentd.conf" error_class=Fluent::ConfigError error="Plugin 'mdsd' does not support multi workers configuration (Fluent::OutputMdsd)"
2020-07-10 07:45:19 +0000 [info]: Received graceful stop
2020-07-10 07:45:19 +0000 [info]: Received graceful stop
2020-07-10 07:45:19 +0000 [info]: Worker 3 finished with status 2
2020-07-10 07:45:19 +0000 [info]: Received graceful stop
2020-07-10 07:45:19 +0000 [error]: #2 config error file="/etc/fluentd/fluentd.conf" error_class=Fluent::ConfigError error="Plugin 'mdsd' does not support multi workers configuration (Fluent::OutputMdsd)"
2020-07-10 07:45:19 +0000 [error]: fluent/log.rb:362:error: config error file="/etc/fluentd/fluentd.conf" error_class=Fluent::ConfigError error="Plugin 'mdsd' does not support multi workers configuration (Fluent::OutputMdsd)"
2020-07-10 07:45:19 +0000 [info]: Received graceful stop
2020-07-10 07:45:19 +0000 [info]: Received graceful stop
2020-07-10 07:45:19 +0000 [info]: Worker 2 finished with status 2
2020-07-10 07:45:19 +0000 [info]: Received graceful stop
2020-07-10 07:45:19 +0000 [info]: Received graceful stop
```

Is it possible to run with multiple workers using mdsd plugin? Have I missed something with my configuration? If not possible, why? Can we add this capability (would love to help with some directions :) )

Thanks in advance