lftp hangs if add strings to source file during transfering

[sherlock-zhouyh]

Use lftp to transfer a big txt file(about 1Gb) in linux: lftp -u mysftp,123456 sftp:xxx.xxx.xxx.xxx:22 -e "debug 10 -cpt -o lftp.log;set net:reconnect-interval-base 3;set net:max-retries 3;set net:timeout 30s;put hello -o share/hello;bye"

Then add bunch of characters to local src file hello during trasfering: echo "testtesttesttesttest...testtestesttesttesttest" >> hello (use scripts to add about 10Mb)

The transfer process will stuck in dead loop(ps -ef|grep lftp).