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Use less subshells and tees in running tests with bazel run.
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Fixes bazelbuild#17754.

What we have seen prior to this change was that sometimes for quick tests the output was swallowed. After a lot of poking it became clear that the culprit is the use of subshell and `tee`, e.g. if you remove `tee` completely from the picture the behavior never shows up.

The issue is that with a fast test, `tee` seems to be killed (or its parent subshell) before the printing the output to stdout.

With this change, we reduce the number of subshells and processes to set up and reduce the chance of the race condition but not remove it.

However, for practical purposes, the race condition is gone.

With the reproduction steps in bazelbuild#17754, and this command
```
for i in {1..10000}; do /tmp/bazel run :foo &> /tmp/log ; grep -q "useful echo" /tmp/log ; if [ $? -eq 0 ]; then echo -n '+'; else  echo -n '-'; fi; done
```
a bazel from head fails ~3900 out of 10000 times.

After this commit, it never failed.

Closes bazelbuild#17846.

PiperOrigin-RevId: 518794237
Change-Id: I8c1862d3a274799b864f0f5f42b85d6df5af78c7
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meisterT authored and copybara-github committed Mar 23, 2023
1 parent c82168e commit c04f0d4
Showing 1 changed file with 2 additions and 2 deletions.
4 changes: 2 additions & 2 deletions tools/test/test-setup.sh
Original file line number Diff line number Diff line change
Expand Up @@ -323,9 +323,9 @@ if [[ "${EXPERIMENTAL_SPLIT_XML_GENERATION}" == "1" ]]; then
fi
else
if [ -z "$COVERAGE_DIR" ]; then
("${TEST_PATH}" "$@" 2> >(tee -a "${XML_OUTPUT_FILE}.log" >&2) 1> >(tee -a "${XML_OUTPUT_FILE}.log") 2>&1) <&0 &
("${TEST_PATH}" "$@" 2>&1 | tee -a "${XML_OUTPUT_FILE}.log") <&0 &
else
("$1" "$TEST_PATH" "${@:3}" 2> >(tee -a "${XML_OUTPUT_FILE}.log" >&2) 1> >(tee -a "${XML_OUTPUT_FILE}.log") 2>&1) <&0 &
("$1" "$TEST_PATH" "${@:3}" 2>&1 | tee -a "${XML_OUTPUT_FILE}.log") <&0 &
fi
fi
childPid=$!
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