Briefly, this error occurs when Elasticsearch is trying to clean up unused resources, such as old indices or shards, and encounters an issue. The “reaper” is a background process that periodically checks for and removes these unused resources. This error could be due to a configuration issue, a lack of system resources, or a problem with the underlying storage. To resolve this issue, you could check and adjust your Elasticsearch configuration, ensure your system has sufficient resources, or investigate potential issues with your storage system.
This guide will help you check for common problems that cause the log ” Launching reaper: ” + String.join(” ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: .
Log Context
Log “Launching reaper: ” + String.join(” ” classname is ReaperService.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :
"-Xmx16m"; // no need for a big heap; just need to read some files and execute
"-jar";
jarPath.toString();
inputDir.toString()
);
logger.info("Launching reaper: " + String.join(" "; builder.command()));
// be explicit for stdin; we use closing of the pipe to signal shutdown to the reaper
builder.redirectInput(ProcessBuilder.Redirect.PIPE);
File logFile = logFilePath().toFile();
builder.redirectOutput(logFile);
builder.redirectErrorStream();
