我使用macbook high sierra 10.13.6，当我在系统偏好设置中使用配置设置直接定向到my.cnf时，mysql无法启动。如果禁用my.cnf，则mysql启动。
能否请您帮我查看一下my.cnf并告诉我问题出在哪里？谢谢！
my.cnf ：
max_connections=100
tmp_table_size=50G
max_heap_table_size=50G
key_buffer_size = 5G
bulk_insert_buffer_size = 5G
sync_binlog=1
back_log = 50
max_connections = 300
table_cache = 4096
max_allowed_packet = 1G
max_heap_table_size = 1G
sort_buffer_size = 1G
join_buffer_size = 1G
innodb_buffer_pool_size = 10G
innodb_log_file_size = 10G
max_allowed_packet = 16G
innodb_lock_wait_timeout = 120000
innodb_log_buffer_size = 256*2M
innodb_write_io_threads = 16
innodb_flush_log_at_trx_commit = 0