Verbose build takes 75x as long as regular build

[rgov]

Configuration

Operating system: macOS 14.1.1 (arm64)

PlatformIO Version: PlatformIO Core, version 6.1.11

Description of problem

Building my project with --verbose significantly increases the time to build.

Steps to Reproduce

I have a very minimal project based on espidf:

platformio.ini

[env:test]
platform = espressif32 @ 5.4.0
framework = espidf

# Settings for ESP32-S3-WROOM-1U-N16
board = esp32-s3-devkitc-1
board_build.flash_mode = dio
board_build.partitions = partitions.csv
board_upload.flash_size = 16MB
board_upload.before_reset = no_reset
board_upload.after_reset = no_reset

Building regularly:

$ pio run -t clean && pio run
...
=== [SUCCESS] Took 22.97 seconds ===

Building verbosely:

$ pio run -t clean && pio run -v
...
=== [SUCCESS] Took 1722.01 seconds ===

[valeros]

Hi @rgov, that's somewhat expected. IDF has hundreds of source files with huge compile commands and every print to the terminal requires some additional processing time. As a workaround just redirect the output to a file pio run > log.txt

[rgov]

I am pretty certain there is a bug here. You can build any number of large programs with verbose output and it does not take 75x as long. The huge compile commands are already constructed in memory, printing them to the terminal takes milliseconds. If it took 5% longer I wouldn't even notice.

Even if verbose build disabled parallel compilation, I would expect like 8x as long to build not 75x as long.

[rgov]

The underlying SCons call on my system when I run pio run -v is:

/opt/homebrew/Cellar/platformio/6.1.11_2/libexec/bin/python \
    /Users/rzg/.platformio/packages/tool-scons/scons.py \
    -Q --warn=no-no-parallel-support --jobs 10 \
    --sconstruct /opt/homebrew/Cellar/platformio/6.1.11_2/libexec/lib/python3.12/site-packages/platformio/builder/main.py \
    PIOVERBOSE=1 ISATTY=1 PIOENV=dGVzdA== \
    PROJECT_CONFIG=L3ByaXZhdGUvdG1wL2JsaW5reS9wbGF0Zm9ybWlvLmluaQ== \
    PROGRAM_ARGS=W10= \
    BUILD_SCRIPT=L1VzZXJzL3J6Zy8ucGxhdGZvcm1pby9wbGF0Zm9ybXMvZXNwcmVzc2lmMzJANS40LjAvYnVpbGRlci9tYWluLnB5

This completes the build in about 20 seconds just like the non-verbose build.

Therefore I think the slowdown involves the buffering of output that platformio does.

[ivankravets]

@rgov thanks for the report. We will fix this issue in PlatformIO Core 7.0 (leveraging asyncio for subprocessing).

[rgov]

@ivankravets See pull request #4786, it's a very simple fix.

[ivankravets]

Did it help you?

[rgov]

Yes, I posted a benchmark showing the issue is resolved. The problem is a buffer that grows unbounded and is reallocated and copied over and over again. At about 2 MB the behavior of this operation in CPython seems to slow down tremendously.