This article explains how Fluentd handles UNIX signals.
When you launch Fluentd, it creates two processes: supervisor and worker. The supervisor process controls the life cycle of the worker process. Please make sure to send any signals to the supervisor process.
Stops the daemon gracefully. Fluentd will try to flush the entire memory buffer at once, but will not retry if the flush fails. Fluentd will not flush the file buffer; the logs are persisted on the disk by default.
Forces the buffered messages to be flushed and reopens Fluentd's log. Fluentd will try to flush the current buffer (both memory and file) immediately, and keep flushing at flush_interval.
Reloads the configuration file by gracefully restarting the worker process. Fluentd will try to flush the entire memory buffer at once, but will not retry if the flush fails. Fluentd will not flush the file buffer; the logs are persisted on the disk by default.