Issue Summary

Full GC and OOME happened when preview pptx with big chart.

The customer is using a pptx file, which contains 17 charts.

If you open pptx file (change extension from pptx to zip, and use unzip command to unzip it), will notice some charts is bigger than 10MB.

It seems very similar to CONFSERVER-52279: PPTX File Conversion Service causes Sustained CPU Spike, OOME if the file contain charts. However, it is closed.  so I created this ticket for tracking this problem.

Steps to Reproduce

1. Upload an pptx with big charts
2. Preview the pptx 

Expected Results

It should be able to preview normally

Actual Results

In customer's production environment, Confluence got unresponsive, full gc observed in customer side.

2021-11-05T17:23:53.441+0900: 391937.741: [Full GC (Allocation Failure)  40846M->24378M(40960M), 31.5930274 secs]
   [Eden: 0.0B(20480.0M)->0.0B(20480.0M) Survivors: 0.0B->0.0B Heap: 40846.8M(40960.0M)->24378.9M(40960.0M)], [Metaspace: 562441K->562433K(602112K)]
 [Times: user=54.07 sys=0.01, real=31.59 secs] 

In my test environment, OOME happened when preview the same pptx attachment.

Workaround

This is likely related to CONFSERVER-61143, as the sandbox process and the file preview process inside Confluence both use the Aspose library. If the issue is reproducible, then it's suggested you try and upgrade to either 7.18.x or 7.13.9 (LTS) in your STAGING environment to see if the issue is resolved and if so take steps to upgrade your production instance.

As a temporary stop-gap, you can try disabling the file preview modules for Slide previewing (pptx files) inside Confluence.
Note this will disable all file previews in Confluence, even for previews that have already been processed. The file will still be accessible through the pages and can still be downloaded locally and previewed, this just affects the preview inside a Confluence page.

1. Log into Confluence as an administrator.
2. Navigate to the cog wheel at the top right, select 'Manage Apps'.
3. Near the search bar, make sure that you change 'User-installed' to 'All Apps'.
4. Search for Confluence Document Conversion Library, click the drop down, select the + sign to show each of the 7 modules.
5. Disable only 'File Conversions', leave the rest of the modules enabled.
6. Next, search for 'Office Connector plugin' and click to drop down the options. Select the + sign to show each of the modules.
7. Disable both PPT slide web service (pptslideservlet) and Office Connector Actions (wordactions), leave the other modules the same.