Summary

Add the command-line switch --exact to the jfr print command.

Problem

The jfr print command allows users to print events from a .jfr file in a human-readable format, for example:

$ jfr print recording.jfr

jdk.FileRead {
  startTime = 16:36:14.373 (2025-04-09)
  duration = 2.02 ms
  path = "/var/folders/g0/cdrkqsy90rz1zq_1c8_xcv4h0000gn/T/+~JF223373.tmp"
  bytesRead = 5.2 MB
  endOfFile = false
  eventThread = "AWT-EventQueue-0" (javaThreadId = 32)
  ...
}

This is usually sufficient to see what is happening, but for verification purposes or correlation with other sources, such as perf output or log files, the exact value is sometimes required. One way to view the exact value is to pass --json to jfr print, which displays the recording in a machine-readable format.

However, this approach makes the output extremely verbose and cumbersome to read. There is a need to display exact values when pretty-printing a recording.

Solution

Add the command-line switch --exact so that jfr print outputs timestamps, time spans, percentages, and byte values with full precision, for example:

$ jfr print --exact recording.jfr

jdk.FileRead {
  startTime = 16:36:14.373600833 (2025-04-09)
  duration = 0.0020170800 s
  path = "/var/folders/g0/cdrkqsy90rz1zq_1c8_xcv4h0000gn/T/+~JF223373.tmp"
  bytesRead = 5458957 bytes
  endOfFile = false
  eventThread = "AWT-EventQueue-0" (javaThreadId = 32)
  ...
}

Specification

src/jdk.jfr/share/classes/jdk/jfr/internal/tool/Print.java

     public List<String> getOptionSyntax() {
         List<String> list = new ArrayList<>();
-        list.add("[--xml|--json]");
+        list.add("[--xml|--json|--exact]");
         list.add("[--categories <filter>]");
         list.add("[--events <filter>]");
         list.add("[--stack-depth <depth>]");
@@ -73,6 +73,8 @@ public void displayOptionUsage(PrintStream stream) {
         stream.println();
         stream.println("  --json                  Print recording in JSON format");
         stream.println();
+        stream.println("  --exact                 Pretty-print numbers and timestamps with full precision.");
+        stream.println();
         stream.println("  --categories <filter>   Select events matching a category name.");