TileMill Export Optimization

[rayan]

I'm currently exporting a medium-sized project to MBTiles on TileMill, using the command line, on a compute-optimized EC2 instance. After monitoring the output of top, it seems the CPU is being underutilized (the server has 32 vCPUs, but CPU usage stays around 900-1200%).

My layers are all being loaded from shapefiles, and I've moved the mapbox file directory from /usr/share/mapbox/ to the instance storage, to take advantage of the SSD for reads and writes.

Is there something in my configuration that's creating a bottleneck? Any suggestions on how to increase the speed?

Some more details about my setup:

Export settings:

• zoom levels: 5 - 7
• bounds: roughly half the size of the continental US
• feature types: polylines and points
• total size of shapefiles: 2 MB
• no basemap, just the shapefile layers
• tile format: 8-bit png
• metatile size: 2

System specs:

• instance type: c3.8xlarge
  • 32 vCPUs
  • SSD drive
  • 60 GB RAM
• OS: Ubuntu 12.04.4

This is the export's current status:

[1h 50m 55s] 5.9367% 17.75m/299.05m @ 2.8k/s | 1d 5h 17m 38s left | ✓ 264.3k ■ 0 □ 17.49m fail 0

Here's the output of sudo perf top:

And here's the output of top:

[rayan]

Here's the CPU utilization according to CloudWatch. Since the export process began, CPU utilization is staying around 30-40%: