if I have multiple Java flight recorder files (.JFR) , how do I merge them together to see them at Java mission control in one time

Question

I received for analysis a bunch of multiple JFR files , like 170 , and it is taking too long to open one by one, can I put them in one single file, starting from the fact that I only have the files and I cannot configure the JVM and obtain the JFR again. for example

2020_03_30_20_37_01_2333_0.jfr
2020_03_30_21_37_01_2333_0.jfr
2020_03_30_22_37_01_2333_0.jfr
2020_03_30_23_37_01_2333_0.jfr

. . .
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Kire Haglin · Accepted Answer · 2020-04-01T17:21:59.387

7

You can use the 'jfr' tool located in JDK_HOME/bin from 11.06 or later.

$ jfr assemble <repository> <file>

where repository is the directory where the files are located and file is the name of the recording file (.jfr) to create.

A recording file is just a concatenation of chunk files so you could do it in the shell as well. For example, using the copy /b command in Windows

 $ copy /b 1.jfr + 2.jfr + 3.jfr combined.jfr

edited Apr 01 '20 at 17:21

answered Apr 01 '20 at 17:16

Kire Haglin

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this would just concatenate the results to a single file or even aggregate the results? – Matécsa Andrea Jul 10 '20 at 10:18
It will just concatenate the result into a single file. Any aggregation is handled by the GUI. – Kire Haglin Jul 10 '20 at 10:22
thank you. What do you mean with the gui? Is there some kind of function to aggregate reocrding files for the same class (for example)? – Matécsa Andrea Jul 10 '20 at 10:25
2

If you use JDK Mission Control, it can show aggregated statistics, for example method profiling aggregated per class or package. – Kire Haglin Jul 10 '20 at 10:30
on linux, you can use `cat jfr_file_version_* >> combined.jfr` – uwevil Jan 07 '21 at 08:39

Leo · Answer 2 · 2020-04-04T08:19:08.070

Here is a script in windows powershell to concatenate the JFR files, just take care of the size of the final concatenated file, it might be too large, in that case you might want to reduce the files to concatenate

    $Location = ""
    $outputConcatenatedJFR = "all_2333_1.jfr"
    $items = Get-ChildItem -Path . -Filter *2333_1.jfr | Sort-Object -Property Name
    New-Item $outputConcatenatedJFR -ItemType file
    ForEach ($item in $items) {
       Write-Host "Processing file - " $item
       cmd /c copy /b $outputConcatenatedJFR+$item $outputConcatenatedJFR
    }

if I have multiple Java flight recorder files (.JFR) , how do I merge them together to see them at Java mission control in one time

2 Answers2