# Proposed changes
This PR fixed lots of issues when building from source on macOS with Apple M1 chip.
## ATTENTION
The job for supporting macOS with Apple M1 chip is too big and there are lots of unresolved issues during runtime:
1. Some errors with memory tracker occur when BE (RELEASE) starts.
2. Some UT cases fail.
...
Temporarily, the following changes are made on macOS to start BE successfully.
1. Disable memory tracker.
2. Use tcmalloc instead of jemalloc.
This PR kicks off the job. Guys who are interested in this job can continue to fix these runtime issues.
## Use case
```shell
./build.sh -j 8 --be --clean
cd output/be/bin
ulimit -n 60000
./start_be.sh --daemon
```
## Something else
It takes around _**10+**_ minutes to build BE (with prebuilt third-parties) on macOS with M1 chip. We will improve the development experience on macOS greatly when we finish the adaptation job.
1. Fix issue #13115
2. Modify the method of `get_next_block` or `GenericReader`, to return "read_rows" explicitly.
Some columns in block may not be filled in reader, if the first column is not filled, use `block->rows()` can not return real row numbers.
3. Add more checks for broker load test cases.
Currently, Doris has a variety of readers for different file formats,
such as parquet reader, orc reader, csv reader, json reader and so on.
The interfaces of these readers are not unified, which makes it impossible to call them through a unified method.
In this PR, I added a `GenericReader` interface class, and other Readers will implement this interface class
to use the `get_next_block()` method.
This PR currently only modifies `arrow_reader` and `parquet reader`.
Other readers will be modified one by one in subsequent PRs.
There is two issue fixed in this pr:
**The first issue** is the C++ code rule of `do not call virtual function in constructor or deconstructor`.
The deconstructor function of `ArrowReaderWrap` call the virtual function named `close()`.
When deconstructing, it will never call `ParquetReaderWrap::close()` just call the `ArrowReaderWrap::close()`
**The second issue** is parallelism deconstructing for `ParquetReaderWrap` and `prefetch_batch`.
`prefetch_batch` use `thread.detach()` to separate the control from `ParquetReaderWrap`, but it rely on some local vars from `ParquetReaderWrap` such as **`_closed ` /`_total_groups ` and `_reader`**
In this case, `ParquetReaderWrap` may call deconstructor before `prefetch_batch` and then get the core dump.
Only support one level array now.
for example:
- nullable(array(nullable(tinyint))) is **support**.
- nullable(array(nullable(array(xx))) is **not support**.
